Overview
The content of vanadium in the earth's crust is about 0.02% of the weight of the crust, which is widely distributed but dispersed. There are 70 kinds of vanadium-containing minerals have been found, wherein the vanadium ore green sulfur, vanadium and vanadium lead zinc ore mica ore containing vanadium oxide, up to 8-20%, of vanadium and titanium ore magnet vanadium low grade, typically containing V2o5 is 0.2-1.4%, but its reserves are the most, and the world reserves are more than 40 billion tons, which is the main raw material for extracting vanadium.
The world's vanadium-iron magnetite and vanadium resources are quite abundant. It has been found that the world's vanadium-iron magnetite reserves are more than 40 billion tons, and are concentrated in a few countries, including the former Soviet Union, the United States, China and South Africa. It is stored in vanadium-titanium magnetite, phosphate rock, uranium- bearing sandstone and siltstone deposits. There are also a large number of vanadium occurs in bauxite and carbonaceous crude oil, coal, oil shale and tar sands.
According to the statistics of the US Bureau of Minerals, according to the current mining scale, the proven vanadium resources can be continuously mined for 150 years and concentrated in South Africa, Asia, North America, etc. (47.0% in South Africa and 24.6% in the former Soviet Union). The United States accounted for 13.1%, China accounted for 9.8%, and other countries accounted for less than 6%.
Vanadium has good plasticity and forgeability, and can be formed into sheets, drawn into filaments and processed into foil at normal temperature. However, a small amount of impurities, especially interstitial elements (such as carbon, hydrogen, oxygen, nitrogen) can significantly affect the physical properties of vanadium. For example, when vanadium contains 0.01% hydrogen, it causes embrittlement and plasticity decreases. When the carbon content is 2.7%, its melting point rises to 2458. K. Vanadium has a high melting point, high hardness, high electrical resistivity, weak paramagnetism, small coefficient of linear expansion, and the elastic modulus density of vanadium is similar to that of steel, and can be used as a structural material.
Vanadium is an important strategic materials, mainly for the metallurgical industry, as an additive alloy elements, the steel structure to improve performance, increase the strength and toughness, followed made of titanium alloys having high temperature and high strength, the chemical industry again It is used as a catalyst for the production of catalysts, catalysts, etc. in the form of vanadium oxide.
The extraction of vanadium abroad is basically recovered from by-products. For example, South Africa, Finland, the former Soviet Union and other countries are recovered from vanadium-titanium magnetite ironmaking. Most of the vanadium in the United States is recovered from potassium vanadium uranium ore and pyrite. Canada is recovered from the dust collected from burning petroleum coke, and a few countries also extract vanadium from stone coal . In short, the world's vanadium is mainly recovered from vanadium-titanium magnetite. The vanadium recovered from vanadium-titanium magnetite is about 70,000 tons per year, accounting for about 70% of the total output.
Vanadium products are divided into primary products, secondary products and tertiary products. Primary products include vanadium-containing minerals, concentrates, vanadium slag, scrapped petroleum refining spent catalysts, scrapping catalysts and other residues. Secondary products include v2o5, which can also be a useful industrial product, namely catalysts for the production of sulfuric acid and catalysts for petroleum refining. Three products include vanadium iron, aluminum, vanadium, molybdenum, vanadium, aluminum, silicon and manganese ferrovanadium vanadium compounds wherein the vanadium iron, vanadium is the most important material, which accounts for 85% consumption of vanadium. National ferro-vanadium standards can be divided into two categories of 50-60% and 70-85%.
China's vanadium industry started in the 1950s. In 1958, the vanadium extraction workshop of Jinzhou Ferroalloy Plant was restored and expanded. The vanadium-bearing iron ore concentrate of Chengde Damiao was used as the raw material for vanadium extraction. After 1960, other vanadium extraction plants in China were completed and put into operation. In the 1970s, Panzhihua Iron and Steel Co., Ltd. was completed and put into production. Since then, China's vanadium industry has entered a new historical period. By the mid-1980s, it has become one of the world's major vanadium-producing countries, capable of producing various vanadium products, and the promotion and application of vanadium has also achieved rapid progress. development of.
The technique for extracting pure vanadium compounds from vanadium-containing raw materials varies depending on the raw materials. Vanadium-titanium magnetite, vanadium-iron concentrate, vanadium-bearing coal, petroleum slag, vanadium uranium ore, vanadium phosphate iron ore, etc., are now described as recycling technologies.
1. Vanadium-titanium magnetite extraction technology:
Vanadium-titanium magnetite extraction can be summarized into two major categories: fire method and wet method. The fire process can process raw materials with low vanadium content, which can be enriched by fire method, and then recycled, also known as the simple connection method; the wet process has the advantages of short process and high recovery rate, but the raw materials required to be processed include The vanadium grade is relatively high, also known as the direct method.
1. Fire process
The selected vanadium iron concentrate is added to the blast furnace or electric furnace ironmaking, and most of the vanadium in the ore enters the molten iron, and the vanadium-containing molten iron is sent into the converter to be blown into steel, and the vanadium is highly concentrated in the surface slag, that is, the vanadium slag. The vanadium slag is crushed, calcined, leached and filtered to obtain V2O5. This is the approach adopted by countries such as the former Soviet Union, Norway and South Africa. A similar method is used in China to recover vanadium.
2, wet process
The vanadium-bearing iron concentrate and the mirabilite -containing bolus, roasting and water immersion are used to make sodium vanadate into the solution, and then sulfuric acid is added to convert it into V2O5 precipitate. After filtration, V2O5 is directly obtained, and the pellet after water immersion is used for the ironmaking raw material. .
South Africa's Hayward is a typical example of the simultaneous application of the above two processes (ie, the pig iron-vanadium slag process and the roasting leaching process).
Pig iron-vanadium slag process
Vanadium-bearing iron concentrate
Silo ingredients
Rotary kiln pre-reduction
Titanium-containing slag ironmaking
Temporary storage of untreated vanadium-bearing molten iron
Slab oxygen blowing for sale
Steel water top blowing steel semi-steel vanadium slag
Billet production V2O5
Roasting leaching process
Vanadium-bearing iron concentrate
H2O Glauber's salt (alkali or Na2SO4) NaCl
Ingredients
Sodium oxidation roasting 1000 ° C
Flooding
Filtration of ammonium salts
Pellet solution
Ironmaking filter H2SO4
Waste ammonium metavanadate
Waste liquid V2O5
The main chemical reaction of leaching of vanadium-bearing iron concentrate or vanadium slag is
(1) 4FeO.V2O3+4Na2CO3+5O2=8NaVO3+2Fe2O3+4CO2
(2) 4FeO.V2O3+8NaCl+5O2=2Fe2O3+8NaVO3+4Cl2
(3) 4FeO.V2O3 +8NH4Cl +5O2=2Fe2O3+8NH4VO3+4Cl2
(4) 2NaVO3+H2SO4=V2O5 + Na2SO4+H2O
(5) 2NH4VO3+H2SO4=V2O5 + (NH4)2SO4+H2O
3, pig iron - vanadium slag process main equipment
1 Mainly based on the main equipment of ironmaking, the former Soviet ironmaking main equipment is blast furnace, and Norway, South Africa and other countries are electric furnaces.
2 Blowing: equipment used in different countries is not consistent
a. Bottom-blown converter for vanadium extraction: The former Soviet Union Chusov United Company is blowing vanadium-containing molten iron into the bottom-blown converter, forming vanadium-containing slag on the oxidized surface of the semi-steel process, and the vanadium slag is crushed, calcined and recovered by water immersion. V2O5 is then refined into ferrovanadium. The total recovery from concentrate to ferrovanadium and vanadium is around 60%.
b. Top-blown converter double vanadium extraction: The former Soviet Union's Lower Tajir Steel Plant used a top-blown converter to blow vanadium-containing molten iron into semi-steel and vanadium slag. The recovery rate of molten iron to vanadium slag vanadium is 92%-94%. China's Chenggang, Maanshan and Panzhihua Iron and Steel Co., Ltd. also use this method to produce vanadium slag, the recovery rate of vanadium is 80% - 88%.
c. The blast furnace molten iron atomization method extracts vanadium. The method actually pours the vanadium-containing molten iron into the intermediate cylinder and then enters the atomizer. After the atomization reaction, the vanadium is oxidized from V2O3 into a mixture of V2O5, V2O4 and V2O3. Semi-steel cylinder, vanadium slag is formed on the semi-steel surface. This method was successfully tested and put into production by China Panzhihua Iron and Steel Co., Ltd., and it is the main method for the production of vanadium slag in China. The oxidation rate of vanadium is 85~90%, the recovery rate is 73.6%, and the recovery rate of semi-steel is 93.9%. The main advantages of this method are: long furnace age (the highest furnace age has reached 12,000 furnaces), large processing capacity (up to 366 tons / hour), semi-continuous production, simple equipment and easy operation.
d. Cao type furnace extraction vanadium: China Maanshan Iron and Steel Co., Ltd. used a trough furnace to extract vanadium. The capacity of the trough furnace is 70T/h. The main technical indicators of the test, the oxidation rate of vanadium is 88.5~95.2%, and the recovery rate of vanadium is 81.3. ~90.49%, the semi-steel rate is 90.20~94.1%, and the production index is not as good as the test index. The method has the advantages of continuous production, simple equipment and low production cost. The disadvantages are that the vanadium slag has high iron content and the vanadium recovery rate is still low. Therefore, it has been discontinued and needs further improvement. It is still one of the best ways to choose.
4, roasting leaching process equipment
The wet process, the core of the roasting leaching process, firstly oxidizes vanadium and then converts it into a water-soluble vanadate, and which roasting equipment is used to achieve its purpose.
a. The vanadium-titanium magnetite component used in the Fantasia plant in South Africa: Fe 50~60%, V2O5 2.5%, TiO2 8~20%, Al2O31~9%, Cr2O31%, rotation kiln roasting to achieve oxidation and conversion.
b. The former Soviet Union and Australia's Agnucliff Co., Ltd. used boiling furnace roasting to convert 97-98% vanadium into soluble vanadium and was leached.
c. Fensheng Ortamaki, using ore concentrate Fe40%, TiO215.5%, VO26% (V2O5: 0.71%) ore group, in the shaft furnace roasting and conversion, the conversion rate of 80~90%.
2. Potassium-vanadium uranium ore and pyrite recovery of vanadium
1. The raw materials processed by American vanadium producers are mainly potassium vanadium uranium ore, uranium molybdenum vanadium ore and pyrite ore. The chemical formula of potassium vanadium uranium ore is K2(VO2)2(V2O8)"3H2O or K2O" 2UO2" V2O5" 3H2O. Recently, large-scale potassium-vanadium uranium deposits have been found in the calcium stone rocks in Elyri, western Australia, and vanadium-uranium symbiotic ores have also been found in Shaanxi and Hunan provinces. The process of producing vanadium from potassium vanadium uranium ore by the United States Union Carbide Corporation, the world's largest mining and metallurgical company, is roasting, leaching, precipitation, reduction and re-leaching. The vanadium uranium leaching rate of this method is 70-80% and 90~95%, respectively. The process is as follows:
Potassium vanadium uranium
6~9% NaCl sodium oxidizing roasting (multi-hearth furnace 850 °C φ5m. 8 layers)
1~2% Na2CO3
Quenching
Leaching
H2SO4 leachate neutralization and boiling
PH: 3
NaOH or NH3 precipitates PH7 vanadium filtrate
Filter cake precipitation
Reduction of vanadium content by Na2CO3 or NaCl reduction
H2O leaching vanadium solution
Uranium-containing sediment recovery of uranium
The vanadium-containing solution is leached by an acid method and an alkali method, and may be separated and purified by an ion exchange method, a solvent extraction method, or a selective precipitation method. The company has an annual output of V2O8454 tons and V2O51360 tons.
2. The treatment of vanadium iron ore is different from that of potassium vanadium uranium. The vanadium iron ore is vacuum extruded and calcined. The mineral powder is mixed with salt, sent to an extruder for extrusion, cutting, and roasting and leaching. After the V2O5.
3. Treatment of vanadium phosphate iron ore
Vanadium-phosphorus iron ore electric furnace produces by-products of elemental phosphorus and phosphate fertilizers (vanadium-containing ferrophosphorus) for vanadium extraction. The vanadium-containing ferrophosphorus used in the US company KerrMeGee Chemical Company contains 3.26%~5.2% vanadium. Phosphorus is 24.7%~26.6%, iron is 59.9%~68.5%, chromium is 3.4%~5.7%, and nickel is 0.84%~1.0%.
First, the vanadium-containing phosphorus iron is ground to a particle size of less than 0.42 mm, and 1.4 times of soda ash and 0.1 times of salt are calcined in a rotary kiln at 770-800 ° C, and the vanadium is converted into a water-soluble sodium salt, and the calcine is leached in boiling water. Vanadium, chromium and phosphorus are dissolved in the leachate. After filtration, the filtrate crystallizes and deducts the sodium phosphate crystals, and the crude sodium phosphate can be further purified until the product is qualified. The sodium phosphate crystallization mother liquor contains phosphorus>0.98g/L. It can be added with appropriate amount of CaCl2 to precipitate calcium phosphate (Ca PO4), then hydrolyzed to recover vanadium, and then lead nitrate is added to the mother liquor to precipitate lead chromate. The recovery of vanadium, chromium and phosphorus in this process can reach 85%, 65% and 94%, respectively.
Third, vanadium-bearing limonite recovery of vanadium technology
The vanadium-containing limonite content of vanadium pentoxide is 0.5~2.5%, Fe20~40%, SiO230~65%.
The ore is mainly composed of goethite, hematite and gangue. The gangue is mainly quartz , followed by mud and a small amount of sericite. Vanadium is not present as an independent mineral in limonite, but is present in iron and mud in an ionic adsorption state. The principle process of the treatment is: crushing ball mill roasting and leaching precipitated Nu4VO3 or V2O5.
Studies have shown that the content of VHO5 in limonite is different, and the conversion rate of vanadium is affected by the composition of ore. The main influencing factor is the content of CaO in ore. As the content of CaO increases, the conversion of vanadium is affected, and the increase of calcination temperature can increase vanadium. Conversion rate. Different vanadium-bearing ores have different temperatures for the highest conversion rates.
4. Vanadium extraction technology for vanadium-containing petroleum slag
Generally speaking, crude oil and oil sands contain vanadium, although some countries have yet to put oil containing vanadium as vanadium resources, but these crude oil is indeed a potential vanadium resources, great changes in the global vanadium content of oil, Venezuela, Crude oil in Mexico, Canada and the United States contains 220-400 ppm of vanadium, which is one of the few countries with high vanadium content in the world.
Countries such as the United States, Japan, Germany, Canada, and Russia extract vanadium from petroleum slag and petroleum ash. The final product of vanadium extraction is mainly V2O5, but it can also be directly converted into ferrovanadium. There are many methods for extraction, and different processes are selected mainly depending on the difference in the composition or properties of the raw materials.
1. Vanadium recovery from oil concentration
The crude oil of Venezuela is cracked to obtain 0.4% V of petroleum coke. The petroleum coke is used as a fuel for steam boilers. After combustion, the dust is collected by an electric dust collector, and the dust contains V2O5 up to 15%, which is used as a raw material for recovering vanadium. The recovery method is to directly soak the collected soot, and the vanadium is oxidized to the pentavalent value by adding the filtered filtrate and sodium hypochlorite (NaClO4), the filtrate is changed from blue to yellow, and the pH is adjusted from 0.3 to 1.7 by adding NH3, so that the vanadium is precipitated as an ammonium salt. Then, the calcined V2O5 or V2O5 melt-casting piece is dried. flow chart:
Petroleum coke dust acid
Leaching
Filtrate residue
ammonia
NaClO4 oxidation precipitation, PH washing
Filter residue washing
Discard
drying
Calcined V2O5
Main chemical reaction: acid leaching process: V2O5+6HCl 2VOCl2+3H2O+Cl2 or V2O5+2H2SO4 VOSO4+2H2O
Oxidation of NaClO4: VOCl2+NaClO4 NaVO3+2NaCl+Cl2VOSO4+NaClO4 NaVO3+NaSO4+Cl2
Precipitation calcination NaVO3+NH4Cl NH4VO3+NaCl2NH4VO3 V2O5+2NH3+H2O
2. Recovery of vanadium from refinery slag
American Amax and CRI Ventures are dealing with refining slag, comprehensive recovery of vanadium, molybdenum, cobalt , nickel and aluminum. The process they treat: refining slag and caustic soda mixed with grinding for pressure leaching, oxidation under high temperature and pressure, sulfur conversion sulfide, most of the hydrocarbon decomposition, vanadium, molybdenum dissolved in the solution, separated by filtration, from the solution Recovery of vanadium molybdenum After the petroleum slag is added with Na2CO3 or NaCl, the electric furnace is smelted in the presence of sulfide and sulfate to obtain vanadium slag and nickel ruthenium. The main processing method of vanadium slag is to prepare industrial V2O5. The United States began to produce vanadium from petroleum slag and petroleum ash in the late 1980s, and it is still the largest producer of vanadium in this raw material.
Five, stone coal extraction vanadium technology
In the census of phosphate rock, it was unexpectedly discovered that the stone coal contains vanadium, and it is found that there are more than 60 kinds of metals and non-metals such as uranium, copper and nickel in the stone coal. As far as the current technical level is concerned, only mining and commercial value are available. vanadium. China's stone coal resources are very rich. It is estimated that the total storage of vanadium in stone coal is seven times the total storage of vanadium in vanadium-titanium magnetite. However, the vanadium grade in stone coal varies greatly from mine to mine. Under current conditions, stone coal contains more than 0.8% vanadium, which has mining value. The vanadium-bearing shale in Nevada, USA is divided into weathered shale (V2O30.93%) and carbonaceous shale (V2O50.84%). China's stone coal resources are concentrated in the southern provinces. There are more than 20 vanadium plants, with an annual output of 2,500 to 3,000 tons and a cost of 2.5 to 300,000 yuan/ton.
The vanadium extraction from stone coal is carried out by adding salt to roast, leaching, extracting and precipitating ammonium metavanadate. The vanadium-bearing carbonaceous shale is decarburization combustion for burning boiler or fluidized bed power. During the combustion process, vanadium is enriched in soot, and vanadium soot is added with NaCl or Na2Co3 for sodium oxide roasting to convert vanadium into Water soluble NaVO3 and Na2V2O5.
4FeOV2O3+4Na2CO3+5O2=4Na2OV2O5+2Fe2O3+4Co2
NaCl+1/2O2= Na2O+Cl2
Na2O+V2O3=2NaVO3
The sodium calcined product is leached with hot water, and sodium vanadate and sodium metavanadate are dissolved in hot water to be separated from most of the insoluble impurities, and the vanadium-containing leaching solution is purified and separated to produce a pure compound of vanadium.
Nevada's vanadium shale vanadium shale process:
shale
↓
Broken, dry
↓
Roasting
↓ H2O
Residue ↠weak acid leaching H2SO4
NH3 ↓
The pH of the leachate except silicon is adjusted from 2.5 to 5.
↙ ↘
Silicon slag vanadium-containing solution PH5 is adjusted back to PH3
↓
Extraction (level 3)
Extraction of organic phase extraction waste
↓
Regeneration extraction ↠secondary stripping ↠NaCO3 solution
Organic phase
Vanadium-containing solution
↓
NH4Cl → ammonium vanadate precipitation
↓
Furnace, washing, drying → waste liquid
↓
Finished ammonium metavanadate
Note: In addition to silicon, the solution needs to be adjusted to pH 5, but the extraction and separation need to be adjusted back to PH3. The extractant used is mixed with tridecylamine (DITDA), and the ammonium metavanadate can be obtained after calcination and deamination. V2O5.
In China, there are factories that extract vanadium from vanadium-bearing coal. Each plant has developed a vanadium-producing process based on its resource characteristics. Their principle process is:
Principle flow of vanadium extraction from stone coal
Stone coal crushing, grinding
↓
Add water → ingredients â†NaCl
↓
Ball
↓
Flat kiln roasting
↓
Flooding
↙ ↘ ↙H2SO4 or HCL
Leaching leaching solution
↙ ↘
Crude vanadium wastewater
↓
NAOH → alkali melting
↓ NH4CL
Water soluble
↙ ↘
Wastewater ammonium metavanadate
↓
Thermal decomposition
↓
Vanadium pentoxide
The new processes for extracting vanadium from stone coal are as follows: 1. Stone coal plus salt, boiling roasting-acid leaching-ion exchange method. 2. Stone coal salt-free roasting - acid leaching - solvent extraction method. 3. Acid leaching - intermediate salt extraction vanadium
The so-called new process of the new process is concentrated on two links. Firstly, the furnace type used for roasting is converted from a flat kiln to a boiling furnace, a rotary kiln, a shaft furnace, etc. As a result, the operating conditions of the shaft furnace are not easily controlled and converted. The rate is unstable, labor conditions are poor, and it has not been widely used in industry. Rotary kiln is widely used in sodium oxidizing roasting of vanadium slag, but stone coal containing silicon (SiO2) is relatively high (65%--68%). It is easy to appear in the process of roasting, such as sticky kiln, ring and shadow rotary kiln. And the conversion rate of vanadium, it is not suitable as a stone coal roasting equipment, as a stone coal roasting equipment is preferably a boiling furnace.
The second environment is the treatment of the solution. In addition to the existing chemical precipitation method, the ion exchange method and the solvent extraction technology are cited. Due to the reference of the new technology, the technical indicators can be improved, the treatment of the wastewater can be reduced, and the operation is different. May affect processing costs.
6. Vanadium extraction technology for spent catalysts and catalysts:
The vanadium compound has good catalytic properties, that is, it does not participate in the chemical reaction itself, but with its participation, the reaction can be accelerated. A chemical agent made of a vanadium compound and its carrier that changes the rate of certain chemical reactions without itself participating in the reaction is called a catalyst. The vanadium catalyst (V2O5•NH4VO3) replaces platinum for the production of sulfuric acid, which converts SO2 to SO3. In the petroleum industry, vanadium is mainly used as a cracking catalyst (VS), as well as a desulfurizing agent. In the rubber industry, a rubber catalyst (VCl4) is combined with the crosslinking of ethylene and propylene. In the chemical industry, benzene is oxidized to maleic anhydride, and vanadium is oxidized to phthalic anhydride (NH4VO3). In particular, the amount of spent vanadium catalyst used in the chemical industry and the petroleum industry is relatively large, and it is a good secondary resource of vanadium, which can not only recover a large amount of vanadium, but also recover nickel and molybdenum equivalent metals.
1. Recovery technology of spent catalyst (VS) for petroleum cracking
The waste vanadium sulfide catalyst is calcined to obtain a product, which can be subjected to a high temperature ammonia leaching method, and the vanadium waste raw material is added to the press, 473. At a temperature of K, the mixture was boiled with ammonia at a concentration of 1-14 MOL/L for 4 hours, and ammonium vanadate was dissolved in aqueous ammonia. After separation by the furnace, the temperature of the ammonium vanadate filtrate was lowered to 323. K, the ammonium vanadate crystal is precipitated, and the crystal slurry is filtered, washed with water, and dried, at 473--873. Calcination at K temperature yields V2O3, and the crystallized mother liquor is returned to the leaching cycle.
In addition to the above methods, vanadium may be recovered from such vanadium waste by alkali leaching using NaOH or Na2Co3 solution at 363-378. The mixture was leached at K temperature for 1-6 hours, then separated by filtration, and ammonia and carbon dioxide were introduced into the immersion liquid to maintain 298--308. K temperature, add 1.5-5 MOL ammonia according to 1 MOL vanadium, and adjust the pH of the solution to 6-9. Treated with ammonia, maintained at 308. K, can precipitate vanadium sulphate. The filtrate is sent to a desorber, and the NH3 and CO2 in the liquid are driven by steam, and then returned to the leaching, and the vanadium sulphate is treated as before.
2. Recovery technology for spent catalyst from crude oil desulfurization:
The spent catalyst is at 1073. Oxidation roasting at K temperature, firstly obtain a calcined material containing vanadium 10.88%, molybdenum 5.49%, cobalt 2.03%, nickel 1.94%, aluminum 35.48%, and then add 300 ml of a solution containing 15% solution of NaOH to 15 g of the calcined material, at 333 . The mixture was leached for 3 hours at a temperature of K, and the leaching solution was at 323. Filtered at K temperature and the leaching solution was 323. K dropped to 278. K, the vanadium-containing crystal is precipitated, the mother liquid is returned to use, and the crystal body is washed with water, dried, and calcined to obtain V2O3.
In addition, the calcined material can also be used in an acid leaching process. In addition to vanadium, the other valuable elements Mo, Ni, Co, etc. are transferred to the flowing liquid, and the vanadium is recovered by extraction and separation after the impurity removal.
U.S. AMR is a vanadium extraction company from petroleum fission waste catalysts. It processes 50% of the spent catalysts and 16,000 tons of spent catalyst annually. It can comprehensively recover 1,500 tons of V2O3, more than 1,000 tons of Mo, 400-600 tons. Ni, 110-180 tons of Co, and some Al2O3.
3. Recovery of vanadium technology from "Sour Acid Waste Catalyst (V2O5, NH4VO3)"
In the sulphuric acid industry, in the catalyst process, since AS2O5 in the SO2 gas forms a complex with V2O5 in the catalyst, the complex volatilizes with the gas at a normal operating temperature of 480 °C. The amount of volatilization accounts for 40-50% of the total amount of V2O5, in addition to K2SO4 and SiO2. The new waste catalyst components are as follows:
Ingredient name V2O5 K2SO4 SiO2
New catalyst component 9---------10% 20-------------22% 20%
Waste catalyst component 5---------6% 10------------12% 80%
Therefore, the three main components in the waste catalyst are valuable resources. For the treatment of waste catalyst, the industry can adopt 1 direct acid leaching process 2 sodium sulphide roasting water immersion process:
Direct acid leaching process: in order to reduce solution impurities and free acid, reduce acid and alkali consumption. Leaching with two stages of countercurrent, one section is weak acid leaching and the second section is high acid leaching. The high acid leachate is added to the newly added spent catalyst for weak acid leaching. The second stage leaching results in vanadium leaching rate of 88.5-91.1%, and the leaching slag containing V2O5 can be reduced to 0.59%. When the second stage leaching acid concentration is increased to 80-100G/T, the slag containing V2O5 can be reduced to 0.3%. The solution is purified by N235 or P204 extraction, alkali stripping, ammonium vanadate with NH4Cl, and calcined to obtain V2O5.
Considering that the direct acid leaching solution removes vanadium, it also contains a large amount of Fe ions, which is troublesome for solution treatment. Oxidation of vanadium into high-valence vanadium by pre-baking, while transforming it, reduces the difficulty of extracting vanadium. Since the waste catalyst itself contains 10% potassium sulfate component, the oxidative roasting water immersion process can be divided into two types: no sodium salt and sodium salt. The former has a calcination temperature of 900 degrees Celsius to achieve an optimum conversion rate (~80%). The conversion of vanadium is not ideal even if the calcination is high or low, and the latter is ideally prepared by adding 5% of Na2CO3 at 800 °C for 2 hours and vanadium conversion of 92%.
Calcination is carried out in two stages of leaching, that is, acid leaching or alkali leaching after water immersion. It is characterized by first immersing potassium salt , sodium salt and nearly 80% vanadium water into a low acid solution. This solution has less impurities and is easy to handle, and the potassium salt can be recycled. The purpose of acid leaching or alkali leaching is to dissolve the vanadium salt which is not tolerable in water as much as possible to increase the recovery of vanadium.
The vanadium in the solution is separated and extracted by N235, the alkali is extracted, the ammonium metavanadate is precipitated by NH4CL, and V2O5 is obtained by calcination.
In short, the choice of process depends on the current situation of the manufacturer, and it is considered that the process of extracting vanadium by sodium oxidizing roasting is better. The material has good filtration performance. The vanadium in the leachate is high in price and has few impurities. The next step of vanadium separation and purification process is easy. It can also directly precipitate ammonium metavanadate with NH4CL, eliminating the extraction process and reducing the processing cost of the product.
Seven. Vanadium iron production technology:
Vanadium and iron form an iron alloy, which is mainly used as an alloying additive in steelmaking, and high vanadium ferrovanadium is also used as an additive for colored alloys. Commonly used vanadium iron contains vanadium 40%, 60% and 80%. The domestic and international processes mainly use electric furnace aluminothermic method and silicon thermal method to smelt vanadium and iron, which are described as follows:
1. Aluminothermic method:
The raw material for smelting vanadium iron by electric furnace aluminizing method may be V2O5 or a mixture of low-valent vanadium oxide (V2O4, V2O3, etc.) or vanadium iron slag. Aluminum is used as a reducing agent under alkaline lining conditions.
Main reaction: V2O5+ AL (bean or granular) = V+AL2O3
V2O4(V2O5)+AL= V+AL2O3
The reaction of smelting ferrovanadium by aluminothermic method is an exothermic reaction, and the reaction speed is fast. Therefore, the V2O5 splashing loss in the smelting process is serious. In order to reduce the loss and increase the recovery rate of vanadium, the V2O5 is specially processed into a sheet shape, and the aluminum grain is changed into aluminum. Beans, appropriate to slow down the reaction and reduce the amount of heat.
When the vanadium oxide is used as a raw material at a low price, the reaction speed in the smelting process is slow, the heat of reaction is appropriate, and the splashing of the process is reduced. Thereby increasing the recovery rate of vanadium, while the iron and vanadium saves 40-60 kg of aluminum reducing agent, vanadium iron contains 60-80% vanadium, and the recovery rate of vanadium is 90-95%.
2. Silicon thermal method:
The essence of the method is that the flake V2O5 is made of 75% ferrosilicon and a small amount of aluminum as a reducing agent, and is purified in a basic electric arc furnace through two stages of reduction and refining. The reduction period is a silicon thermal reduction of the reducing agent and V2O5. When the V2O5 in the slag is less than 0.35%, it can be treated as waste residue (or used as building materials). As a smelting operation, it can be transferred to the refining period. At this time, some V2O5 and CaO are added to remove the alloy liquid. Excess silicon, aluminum, etc. When the alloy composition meets the requirements, the slag can be discharged and the gold is contained. During the refining period, the slag contains V12O5 up to 8-12%, and the slag can be returned to the smelting reduction period for recovery. The alloy liquid can be cast into a round ingot and then broken into finished products. The ferrovanadium produced by this method contains 40-60% vanadium and the vanadium yield can reach 98%.
In addition, high vanadium iron, silicon vanadium iron, silicon manganese vanadium iron, vanadium carbide, vanadium carbonitride, ferrogang nitride and metal vanadium have been developed and will not be described here.
Eight, a few points:
1. According to the vanadium-containing raw materials used: vanadium-containing iron water, vanadium iron concentrate, vanadium slag, vanadium uranium iron ore, vanadium phosphate iron ore, vanadium-bearing coal, vanadium-bearing limonite, vanadium-containing petroleum slag, and chemistry Waste catalysts used in petroleum and rubber industries.
2. The process of extracting vanadium generally consists of four steps: calcination, leaching and purification, extraction of vanadium in solution and extraction of tail liquid. The first two steps are most important:
1 Sodium oxide roasting: The vanadium-containing raw material and sodium salt such as Na2CO3 NaCl and Na2SO4 are mixed in a rotary kiln, a shaft furnace, a flat kiln, a multi-hearth furnace or a boiling furnace at 800-1000. Oxidation and conversion are carried out under C to convert vanadium into XNa2O•YV2O5 to dissolve in water.
In some cases, the vanadium-containing material may be added with lime or lime milk (Ca(0H)2) ​​and calcined in the above various furnaces. The purpose is opposite to that of sodium roasting, which converts sodium into water-insoluble, but Dissolved in carbonate solution to form calcium vanadate for separation from other impurities.
2 Leaching: roasting clinker leaching: water immersion, acid leaching, alkali leaching and carbonation leaching, etc., in the case of water immersion, sodium vanadate enters the solution, acid leaching is different, there are three ways: A, vanadium Direct acid pickling of materials; B, acid leaching of vanadium-containing materials after roasting; C, vanadium-containing clinker after acid leaching and acid leaching, acid leaching can also be applied to other materials, potassium vanadium uranium ore, phosphorus vanadium iron Mine, vanadium-containing ash, waste vanadium catalyst, etc. Commonly used alkali leaching agents are NaOH, Na2CO3 or a mixture of the two, etc., and alkali leaching must also make vanadium into a high valence state. The oxidant includes oxygen, air, oxygen-enriched air, sodium peroxide, chlorine, sodium hypochlorite, potassium permanganate, and the like.
Solution purification: the vanadium-containing leaching liquid suspension can be removed by clarification to remove Fe, Mn, Si, and Al. The precipitate can be removed by precipitation with calcium salt and magnesium salt. Electrolytic solution can be used for sodium removal and recovery of high alkalinity solution. Alkali.
3 Extraction of vanadium in solution: precipitation method, solvent extraction and ion exchange method
Precipitation: A, ammonium salt precipitation: the formation of ammonium polyvanadate (NH4) 2V6O16 precipitation, the formation of Na2 (NH4) 4V10O28.11H2O precipitation, the formation of ammonium metavanadate NH4VO3 precipitation.
B. Hydrolysis precipitation: H2SO4 was added to precipitate a red vanadate precipitate, Na2H2-X.V12O31.
C, calcium salt or iron salt precipitation: alkaline solution with CaCl2 or other CaO, Na (OH) 2 precipitated calcium vanadate, or high iron salt precipitation of iron vanadate (XFe2O3 • YV2O5 • 2H2O).
Solvent extraction: separation of vanadium and uranium: using tributyl hexyl phosphate and N235
Ion exchange: suitable for treating alkaline solutions
4 tail liquid treatment: pentavalent vanadium and hexavalent chromium ion free acid, salt are toxic, must be handled before they can be eliminated, there are three treatment methods in the industry:
A, reduction and elimination method
B. Sulfur dioxide reduction method in gas
C, ion exchange method
3. The proven vanadium reserves are used for 150 years according to the current mining scale. The annual output of vanadium is in a state of balance between supply and demand. The supply and demand of vanadium varies with the output of alloy steel.
Polyester Twisted Yarn ITY Made of one-step self-produce ITY, material lot number is very stable, whole year don't change, normal twist range 600TPM to 1200TPM, it is widely used in weaving and knitting, fabric with good drape, mainly used in women's clothing. Capacity more than 600 tons per month, can deliver very fast.
Polyester Lycra Fabric,ITY Polyester Fabric,Polyester Twisted Yarn Ity,Polyester Ity Twisted Yarn
YIBIN MERRY TRADING CO. LTD. , https://www.cnmerry.com