NZ586447A

NZ586447A - Method for producing vanadium products by fluidization technique

Info

Publication number: NZ586447A
Application number: NZ586447A
Authority: NZ
Inventors: Yi Peng; Yiping Zhou; Shengyou Zhu; Fan Zhang; Zhaohui Sun; Jing Wang
Original assignee: Pangang Group Steel Va & Ti Co; Pangang Group Co Ltd
Priority date: 2007-11-26
Filing date: 2008-10-21
Publication date: 2011-10-28
Also published as: WO2009071006A1; RU2441083C1; CN101245410A; ZA201002349B; CN100582257C

Abstract

A method for producing vanadium products by a fluidization technique is disclosed, wherein the method comprises the following steps:(a) preparing for high-calcium vanadium slags having CaO/V2O5 weight ratio not less than 0.5 but not more than 0.7; (b) roasting the high-calcium vanadium slags in a fluidized bed furnace to obtain roasted clinker (wherein the mean temperature in the fluidized bed furnace is around 850 Deg C to 950 Deg C, and the mean residence time of the vanadium slags in the fluidized bed furnace is 30min-150min); and (c) leaching the roasted clinker in sulfuric acid solution, and further preparing the vanadium products from leach liquor. Another method for producing vanadium products by a fluidization technique is also disclosed, wherein step (a) involves preparing for high-calcium vanadium slags having CaO/V2O5 weight ratio more than 0.7 but not more than 1.4, followed by the steps of roasting, leaching and preparing the vanadium products.

Description

<div class="application article clearfix" id="description"> New Zealand Paient Spedficaiion for Paient Number 586447 Received at IPONZ on 16-Aug-2011 Method for Producing Vanadium Products by Fluidization Technique Field of the Invention The invention relates to a method for producing vanadium products by a fluidization technique and belongs to a vanadium extraction technique. Technical Background Vanadium slags are a kind of vanadium-enriched material converted from vanadium-bearing hot metals by using gases containing oxygen such as oxygen or oxygen-enriched air. Vanadium in ordinary vanadium slags is mainly present in ferrovanadium spinels in the trivalent form, chemical formula of ferrovanadium can be expressed as Fe0V203, and a small amount of calcium is present in silicate phase. The ordinary vanadium slags are divided into 7 designations according to grades of vanadium pentoxide, and chemical compositions of the ordinary vanadium slags should meet requirements of Table 1. Table 1 Chemical compositions, % Si02 P Ca0/V205 Designation v2o5 Grade Grade Grade Grade Grade Grade Grade Grade Grade 1 2 3 1 2 3 1 2 3 < FZ9 8.0-10.0 FZ11 10.0-12.0 FZ13 12.0-14.0 FZ15 14.0-16.0 16.0 20.0 24.0 0.13 0.30 0.50 0.11 0.16 0.22 FZ17 16.0-18.0 FZ19 18.0-20.0 FZ21 >20.0 From the above Table, the standard for the ordinary vanadium slags has strict requirements for the content of CaO in the vanadium slags, the Ca0/V205 ratio of Grade 1 vanadium slags is required to be not more than 0.11 or that of Grade 3 vanadium slags to be not more than 0.22 at most. Generally, the traditional process of vanadium extraction by sodium roasting and water leaching of vanadium slags is used to produce vanadium products such as vanadium oxide, ferrovanadium, vanadium nitride products from the ordinary vanadium slags. For example, Pangang Group Company Ltd. and Chenggang Group in China, Nizhny Tagil and JSC Chusovskoi Iron and Steel Works in Russia, Highveld Steel and Vanadium Corp. l Received at IPONZ on 16-Aug-2011 Ltd. in South Africa, and New Zealand Steel Mining Limited, etc., use the process. The process comprises the following steps: evenly mixing the crushed vanadium slags with sodium salt such as Na2CC>3, adding the mixture to a rotary kiln or a multiple-hearth furnace, gradually heating from low temperature of 200°C-300°C to 760°C-850°C, and roasting for 2h-5h usually. The roasted product is discharged from the furnace and called clinker or calcining, and the clinker is dissolved and leached in water to allow water soluble sodium vanadate to be transferred to solution for further preparing vanadium products. Another process is a calcified roasting-sulfuric acid leaching process which is used by JSC Vanady-Tula in Russia. The process comprises the following steps: roasting a lime substance as an additive together with the crushed vanadium slags in the rotary kiln or the multiple-hearth furnace, also gradually heating from the low temperature of 200°C-300°C to 880°C-950°C, keeping 880°C-950°C for lh-3h, and then discharging the mixture from the furnace to obtain so-called calcified roasted clinker. Vanadium in the clinker is present in the form of calcium vanadate or calcium manganese vanadate, and is taken into the solution by dissolving and leaching in sulfuric acid solution for further preparing the vanadium products. The calcified roasting-sulfuric acid leaching process is advantageous in that waste water can more easily reach the national discharge standard compared with the sodium roasting process. As the calcified roasting process uses the lime substance as the roasting additive, content of CaO in the vanadium slags is not strictly required and can reach 4.5%-5.5%. JSC Vanady-Tula in Russia requires Ca0/V205 ratio to be 0.7-0.75 and roasting temperature to be 800-860°C (Russian patent No. 97113072/02), and requires to add proper amount of lime and residue leached by sulfuric acid. All vanadium plants in the world use the rotary kiln or the multiple-hearth furnace as roasting equipment regardless of the sodium roasting and water leaching process or the calcified roasting and sulfuric acid leaching process, and no plant uses the fluidization technique and the fluidization equipment to roast the vanadium slags, because the additive (sodium salt or calcium salt) is necessary for both the sodium roasting and water leaching process and the calcified roasting and sulfuric acid leaching process and is greatly different from the vanadium slags with regard to fluid mechanical properties, and vanadium-bearing raw materials can not be evenly mixed and react with the additive in the fluidized bed furnace, which easily causes segregation and results in rather poorer roasting effect than that of the rotary kiln or the multiple-hearth furnace. Therefore, the 2 Received at IPONZ on 16-Aug-2011 rotary kiln or the multiple-hearth furnace is usually used for roasting. In the past, some people studied a technique of roasting mixture of vanadium titano-magnetite and sodium chloride by the fluidization equipment, but the technique results in serious segregation and very poor effect, so the technique can not be applied to production. For the above reasons, up to now, there is no related report on producing the vanadium products by roasting high-calcium vanadium slags by the fluidized bed furnace. The fluidized bed furnace has very high heat transfer efficiency, mixes particles evenly and has relatively even temperature field therein; thus the fluidized bed furnace has advantages of short reaction time, adequate contact of materials and oxygen, low energy consumption, high production efficiency and high equipment capacity in the case of the same physical volume compared with the rotary kiln, the multiple-hearth furnace and the shaft furnace. Therefore, the fluidization technique and equipment, if used for roasting the vanadium slags, are more advantageous than the rotary kiln or the multiple-hearth furnace. To realize fluidized roasting, a problem to be solved is to evenly mix the vanadium-bearing raw materials and the additive. Enough lime substance is added while converting vanadium from the vanadium-bearing hot metal to obtain calcium-enriched vanadium slags which are called the high-calcium vanadium slags. Most vanadium in the high-calcium vanadium slags is still present in the ferrovanadium spinels, and calcium is mainly present in the silicate phase. The fluidized roasting of the high-calcium vanadium slags will result in a significant innovation in the vanadium extraction technique. Summary of the Invention A technical problem to be solved by the invention is to overcome disadvantages of high energy consumption, low efficiency, low unit equipment capacity, etc. in producing vanadium products from vanadium slags by the prior art and provides an efficient and energy-saving method for producing vanadium products with good oxidation effect; and/or at least provides the public with a useful choice. The invention is characterized by taking high-calcium vanadium slags as the raw material, adding no additive for fluidized roasting, evenly mixing and adequately roasting the material in a fluidized bed furnace to allow smooth reaction of converting vanadium into calcium vanadate and calcium manganese vanadate, which results in a significant renovation of in the vanadium extraction technique. In a first aspect, the present invention provides a method for producing vanadium 3 Received at IPONZ on 16-Aug-2011 products by a fluidization technique, comprising the following steps: a. preparing for high-calcium vanadium slags having CaO/V205 weight ratio not less than 0.5 but not more than 0.7; b. roasting the high-calcium vanadium slags in a fluidized bed furnace to obtain roasted clinker; and c. leaching the roasted clinker in sulfuric acid solution, and further preparing the vanadium products from leach liquor. In a second aspect, the present invention provides a method for producing vanadium products by a fluidization technique, comprising the following steps: a. preparing for high-calcium vanadium slags having Ca0/V205 weight ratio more than 0.7 but not more than 1.4; b. roasting the high-calcium vanadium slags in a fluidized bed furnace to obtain roasted clinker; and c. leaching the roasted clinker in sulfuric acid solution, and further preparing the vanadium products from leach solution. The invention also provides vanadium products, when obtained by a method according to the first or second aspect. Some embodiments of the invention are realized by the following technical scheme: a. preparing for high-calcium vanadium slags having CaO/V2O5 weight ratio of 0.5-1.4 (that is, 0.5<ca0/v205<0.7 and 0.7< Ca0/V205<1.4), preferably 0.66-1.3 (that is, 0.66<ca0/v205<0.7 and 0.7<CaO/V2O5<1.3), more preferably 0.8-1.19; b. roasting the high-calcium vanadium slags in a fluidized bed furnace with the mean temperature of 850°C-950°C (preferably 880°C-940°C) and mean residence time of 30min-150min (preferably 50min-120min) to obtain roasted clinker; wherein the fluidized bed furnace can be charged with excessive air or oxygen-enriched air to improve oxidation effect; for example, coal gas, natural gas and fuel oil are burned, then mixed with air and charged into the fluidized bed furnace for heating the material, ensuring enough oxidizing atmosphere in the furnace to oxidize quadravalent vanadium to pentavalent vanadium and further produce vanadate; and c. leaching the roasted clinker in sulfuric acid solution, and further preparing the vanadium products from leach solution. Further, in order to oxidize ferrovanadium spinels more easily, the high-calcium vanadium slags of step a can be crushed to less than 0.125mm, and more than 95% of 4 Received at IPONZ on 16-Aug-2011 particles have diameters less than 0.1mm. The leaching in step c can be realized by the following scheme: adding 1-4 times of water (by weight) to the roasted clinker to prepare slurry, then adding 10%-65% (preferably 32%-65%) sulfuric acid solution to adjust pH value of the slurry for leaching while keeping the pH value in the range of 2.8-3.3 at 30°C-60°C for 30min-90min during the leaching period. Beneficial effects of the invention are as follows: 1. The vanadium slags are mixed very evenly and quickly in the fluidized bed furnace, thus resulting in very good mass and heat transfer effects and being capable of obviously shortening roasting time and reducing energy consumption and production cost of the roasting process. 2. As the fluidized bed furnace with gas as a motion carrier is used as roasting equipment, excessive air or oxygen-enriched air can be charged to improve oxidization effect, shorten roasting time and reduce energy consumption. 3. The capacity of the fluidized bed furnace is 6-10 times higher than that of the rotary kiln and the multiple-hearth furnace in the case of same volume of equipment, therefore, using the fluidized bed furnace can greatly increase capacity of a single set of equipment, reduce equipment investment and improve production capacity and economic benefits of enterprises. 4. The rotary kiln, the multiple-hearth furnace and the shaft furnace or a certain main part of the equipment need motion, the fluidized bed furnace takes gas as the carrier, only the material moves in the equipment, and the equipment has fewer moving parts, thus damage and maintenance of the equipment are greatly reduced, which benefits organization and implementation of production. Detailed Description of the Invention The invention is further illustrated below by reference to the following Examples. The Examples are only for description of the invention instead of limitation of the invention in any manner. Example 1: Effect of Ca0/V205 weight ratio of high-calcium vanadium slags on vanadium conversion and leaching efficiency 400kg high-calcium vanadium slags (CaO/V2O5 weight ratios are shown in Table 2) are ground to less than 0.125mm, and 95% of particles have diameters less than 0.1mm. 5 Received at IPONZ on 16-Aug-2011 The vanadium slags are added to a ® 100x2500mm fluidized bed furnace in the manner of top charging and bottom discharging. Coal gas is burned, mixed with excessive air to form high-temperature oxidizing hot air and then is charged from the lower portion of a furnace tube. Flow of the hot air and charging amount of the vanadium slags are adjusted to keep the vanadium slags in a better state of agitation in the furnace, the mean temperature in the fluidized bed furnace is controlled at 900°C, and the mean residence time of the vanadium slags in the furnace is controlled at 30min.The roasted clinker is discharged from an outlet at the lower portion of the fluidized bed furnace, rapidly cooled and crushed to less than 40 meshes, added with water 3 times of clinker (by weight) to prepare slurry, and then added with 65% sulfuric acid to adjust pH value of the solution for leaching while keeping the pH value in the range of 2.8-3.3 at 30°C-60°C for 60min during the leaching period. Residue is filtered, washed and then dried for analysis of vanadium content and determination of vanadium leaching efficiency of the high-calcium vanadium slags. Results are shown in Table 2. Table 2 Ca0/V205 Vanadium conversion and leaching efficiency, % 0.52 76.40 0.66 80.03 0.80 89.89 0.91 86.24 0.98 88.15 1.19 84.23 1.36 71.72 2.61 66.55 From Table 2, the roasting effect is best when CaO/VSOs ratio of the high-calcium vanadium slags is 0.8-1.19, and the roasting-leaching effect of the high-calcium vanadium slags weakens when the Ca0/V205 ratio is less than 0.66 and more than 1.19. Example 2: Production of V205 from high-calcium vanadium slags 400kg high-calcium vanadium slags (CaO/VSOs weight ratio is 0.91 and V2O5 content is 11.54%)) are ground to less than 0.125mm, and 95% of particles have diameters less than 0.1mm. The vanadium slags are added to a ® 100x2500mm fluidized bed furnace in the manner of top charging and bottom discharging from the top. Coal gas is burned, mixed with excessive air to form high-temperature oxidizing hot air and then charged from the lower portion of a furnace tube. Flow of the hot air and the amount of the charged vanadium 6 Received at IPONZ on 16-Aug-2011 slags are adjusted to keep the vanadium slags in a better state of agitation in the furnace, the mean temperature in the fluidized bed furnace is controlled at 900°C, and the mean residence time of the vanadium slags in the furnace is controlled at 30min. The roasted clinker is discharged from an outlet at the lower portion of the fluidized roaster, rapidly cooled and crushed to less than 40 meshes. The clinker (200g) is added with 3 times of water (by weight) to prepare slurry, and then added with 65% sulfuric acid to adjust pH value of the solution for leaching while keeping the pH value in the range of 2.8-3.3 at 30°C-60°C for 60min during the leaching period. Residue is filtered, washed and then dried for analysis of vanadium content, and the leaching efficiency of vanadium in the high-calcium vanadium slags is measured as 87.19%. pH of filtrate is adjusted to 2.0 by sulfuric acid, then the filtrate is heated to boil, insulated for 60min and filtered, precipitate is washed, then dried and calcined to obtain 29.49g of V205 with the purity of 94.01%). Example 3: Production of V2Os from high-calcium vanadium slags 500kg high-calcium vanadium slags (Ca0/V205 weight ratio is 0.66 and V2Os content is 12.84%o) are ground to less than 0.125mm, and 95% of particles have diameters less than 0.1mm. The vanadium slags are added to a ® 100x2500mm fluidized bed furnace in the manner of bottom charging and top discharging from the bottom. Coal gas is burned, mixed with excessive air to form high-temperature hot air and then charged from the lower portion of a furnace tube. Flow of the hot air and the amount of the charged vanadium slags are adjusted to keep the vanadium slags in a better state of agitation in the furnace, the mean temperature in the fluidized bed furnace is controlled at 850°C, and the mean residence time of the vanadium slags in the furnace is controlled at 150min. The roasted clinker is discharged from an outlet at the upper portion of the fluidized bed furnace, rapidly cooled and crushed to less than 40 meshes. The clinker up to 400g is added with 4 times of water (by weight) to prepare slurry, and then added with 65 % sulfuric acid to adjust pH value of the solution for leaching while keeping the pH value in the range of 2.8-3.3 at 30°C-60°C for 30min during the leaching period. Residue is filtered, washed and then dried for analysis of vanadium content, and the vanadium leaching efficiency of the high-calcium vanadium slags is measured as 84.74%. pH of filtrate is adjusted to 2.0 by sulfuric acid, then the filtrate is heated to boil, insulated for 60min and filtered, and precipitate is washed, then dried and calcined to 7 </div>

Claims

Received at IPONZ on 16-Aug-2011 obtain 44.57g of V205 with the purity of 93.2%. Example 4 Production of V2Os from high-calcium vanadium slags 300kg high-calcium vanadium slags (Ca0/V205 weight ratio is 0.7 and V2Os content is 12.68%) are ground to less than 0.1mm. The vanadium slags are added to a ® 100x2500mm fluidized bed furnace in the manner of top charging and bottom discharging from the top. Coal gas is burned, mixed with excessive air to form high-temperature hot air and then charged from the lower portion of a furnace tube. Flow of the hot air and charging amount of the vanadium slags are adjusted to keep the vanadium slags in a better state of agitation in the furnace, the mean temperature in the fluidized bed furnace is controlled at 930°C, and the mean residence time of the vanadium slags in the furnace is controlled at 90min. The roasted clinker is discharged from an outlet at the lower portion of the fluidized bed furnace and rapidly cooled. The clinker( 200g)is added with 2 times of water (by weight) to prepare slurry, and then added with 32% sulfuric acid to adjust pH value of the solution for leaching while keeping the pH value in the range of 2.8-3.3 at 30°C-60°C for 30min during the leaching period. Residue is filtered, washed and then dried for analysis of vanadium content, and the vanadium leaching efficiency of the high-calcium vanadium slags is 85.18%). pH of filtrate is adjusted to 2.0 by sulfuric acid, then the filtrate is heated to boil, insulated for 60min and filtered, and precipitate is washed, then dried and calcined to obtain 21.89g of V205 with the purity of 93.65%). The term "comprising" as used in this specification and claims means "consisting at least in part of'. When interpreting statements in this specification and claims which include the term "comprising", other features besides the features prefaced by this term in each statement can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in similar manner. In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art. 8 Received at IPONZ on 16-Aug-2011 What we claim is:

1. A method for producing vanadium products by a fluidization technique, comprising the following steps: a. preparing for high-calcium vanadium slags having CaO/V2O5 weight ratio not less than 0.5 but not more than 0.7; b. roasting the high-calcium vanadium slags in a fluidized bed furnace to obtain roasted clinker; and c. leaching the roasted clinker in sulfuric acid solution, and further preparing the vanadium products from leach liquor.

2. The method for producing vanadium products by a fluidization technique according to claim 1, wherein the high-calcium vanadium slags in step a have CaO/VSOs weight ratio not less than 0.66 but not more than 0.7.

3. A method for producing vanadium products by a fluidization technique, comprising the following steps: a. preparing for high-calcium vanadium slags having CaO/VSOs weight ratio more than 0.7 but not more than 1.4; b. roasting the high-calcium vanadium slags in a fluidized bed furnace to obtain roasted clinker; and c. leaching the roasted clinker in sulfuric acid solution, and further preparing the vanadium products from leach solution.

4. The method for producing vanadium products by a fluidization technique according to claim 3, wherein the high-calcium vanadium slags in step a have Ca0/V205 weight ratio more than 0.7 but not more than 1.3.

5. The method for producing vanadium products by a fluidization technique according to any one of claims 1-4, wherein: the high-calcium vanadium slags in step a are crushed to less than 0.125mm before being added to the fluidized bed furnace, and more than 95% of particles have diameters less than 0.1mm.

6. The method for producing vanadium products by a fluidization technique according to any one of claims 1-4, wherein: in step b, the mean temperature in the fluidized bed furnace is 850°C-950°C, and the mean residence time of the vanadium slags in the fluidized bed furnace is 30min-150min.

7. The method for producing vanadium products by a fluidization technique 9 Received at IPONZ on 16-Aug-2011 according to claim 6, wherein: in step b, the mean temperature in the fluidized bed furnace is 880°C-940°C, and the mean residence time of the vanadium slags in the fluidized bed furnace is 50min-120min.

8. The method for producing vanadium products by a fluidization technique according to any one of claims 1-4, wherein: in step b, coal gas, natural gas and fuel oil are burned, mixed with air and then charged into the fluidized bed furnace for heating material and ensuring enough oxidizing atmosphere in the furnace.

9. The method for producing vanadium products by a fluidization technique according to any one of claims 1-4, wherein: in step c, the roasted clinker is added with water to prepare slurry, and then added with 10%-65% sulfuric acid to adjust pH value of the solution for leaching while keeping the pH value in the range of 2.8-3.3 at 30°C-60°C for 30min-90min during the leaching period, and further preparing V2O5 from the leach solution.

10. The method for producing vanadium products by a fluidization technique according to any one of claims 1-4, wherein: in step c, concentration of the sulfuric acid for adjusting pH value of the solution is 32-65%.

11. Vanadium products, when obtained by a method according to any one of claims 1. -10.

12. A method, as defined in claim 1 or 3, substantially as herein described with reference to any example thereof. 10