Roasting method of vanadium slag

Abstract

The invention relates to a roasting method of vanadium slag, in particular to the field of vanadium extraction from the vanadium slag, and the roasting method comprises the following steps: mixing the vanadium slag and sodium salt, and then roasting to obtain a roasted material; the roasting comprises the steps of heat preservation and cooling which are performed in sequence; the cooling rate of cooling is greater than or equal to 40 DEG C / min. According to the roasting method provided by the invention, the defect that the vanadium dissolution effect becomes poor due to the fact that vanadium bronze is formed by roasted materials is avoided by means of specific cooling after heat preservation, and the conversion rate of vanadium in the vanadium slag can reach 90% or above.

Description

Technical Field

[0001] The invention relates to the field of vanadium extraction from vanadium slag, and in particular to a roasting method for vanadium slag. Background Art

[0002] Currently, steel mills typically use an indirect vanadium extraction method using vanadium slag as raw material for vanadium recovery. After finely grinding the vanadium slag for iron selection, a sodium salt additive is added proportionally. The slag is then calcined in a rotary kiln to convert insoluble vanadium compounds into soluble sodium vanadate. This solution is then leached in water to form a sodium vanadate solution. After purification and phosphorus removal, sulfuric acid and ammonium sulfate are added to the solution under heating to precipitate ammonium salts, producing ammonium polyvanadate. The ammonium polyvanadate is then decomposed, melted, and cast into flakes to produce vanadium pentoxide.

[0003] For example, CN117701915A discloses a vanadium extraction method using low-calcium staged roasting of vanadium slag, comprising: oxidative roasting of a uniformly mixed mixture of vanadium slag and a calcium salt additive to obtain calcified clinker; leaching the calcified clinker followed by solid-liquid separation to obtain an acidic vanadium-containing solution and a residue; precipitation-calcining the acidic vanadium-containing solution to obtain a vanadium oxide product, and high-temperature roasting of the residue to obtain a roasting residue; leaching the roasting residue followed by solid-liquid separation to obtain a low-vanadium solution and vanadium extraction tailings.

[0004] CN106011493A discloses a roasting method for low-grade vanadium slag, belonging to the technical field of vanadium chemical industry, comprising the following steps: crushing the low-grade vanadium slag, uniformly mixing it with tailings and vanadium-containing waste to obtain a mixture, adding an additive to the mixture and continuing to mix it, and then aerobic roasting to obtain roasted clinker.

[0005] However, the existing roasting methods still have the disadvantages of poor roasting conversion effect when roasting vanadium slag containing calcium, chromium and silicon, which is not conducive to vanadium recovery. Summary of the Invention

[0006] In view of the problems existing in the prior art, the object of the present invention is to provide a method for roasting vanadium slag to solve the defect that roasting vanadium slag containing calcium, chromium and silicon still has poor roasting conversion effect and is not conducive to vanadium recovery.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for roasting vanadium slag, which comprises:

[0009] Mixing vanadium slag and sodium salt, and then roasting to obtain a roasted material;

[0010] The roasting comprises: sequentially carrying out heat preservation and cooling;

[0011] The cooling rate is ≥40°C / min.

[0012] The roasting method provided by the present invention avoids the defect that the material forms vanadium bronze after roasting and causes poor vanadium dissolution effect by specifically cooling the temperature after roasting. The conversion rate of vanadium in vanadium slag can reach more than 90%.

[0013] As a preferred technical solution of the present invention, the vanadium slag comprises, by mass percentage, the following: Ca 2.5-4%, Cr 9-15%, Si 12-17%, Fe 3-5%, and V 11.5-14.5%.

[0014] Preferably, the D85 particle size of the vanadium slag is 0.05-0.2 mm.

[0015] As a preferred technical solution of the present invention, the sodium salt includes: sodium carbonate.

[0016] As a preferred technical solution of the present invention, the mass ratio of sodium salt to vanadium in the mixed material calculated as vanadium pentoxide is (1.3-1.5):1.

[0017] As a preferred technical solution of the present invention, the insulation temperature is 800-900°C.

[0018] As a preferred technical solution of the present invention, the insulation time is 2-2.5h.

[0019] As a preferred technical solution of the present invention, the temperature of the material obtained by cooling is 100-300°C.

[0020] As a preferred technical solution of the present invention, the roasted material is immersed in water to obtain a leachate.

[0021] As a preferred technical solution of the present invention, the leaching solution is subjected to ammonium salt precipitation to recover vanadium elements.

[0022] As a preferred technical solution of the present invention, the leached residue obtained from the water leaching is returned for roasting.

[0023] Compared with the existing technical solutions, the present invention has the following beneficial effects:

[0024] The roasting method provided by the present invention performs specially designed cooling after the roasting heat preservation, thereby avoiding the formation of stable crystalline substances by vanadium, chromium, silicon and calcium in the conventional vanadium slag of the roasted material, which is converted into substances that are not conducive to leaching, affecting the leaching effect of vanadium and being not conducive to vanadium recovery. The roasted material obtained after cooling has a vanadium conversion rate of ≥90%, and the vanadium leaching rate of the obtained roasted material in water leaching is ≥90%.

[0025] The present invention is further described in detail below. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0026] To better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0027] At present, when vanadium slag with high calcium, silicon and chromium content is roasted, the V conversion rate continues to decrease as the CaO content increases; for every 1% increase in CaO, soluble vanadium is lost by 1-2%. When the CaO content increases to 3.0, the conversion rate drops to 77%, and the silicon element reacts with the sodium salt to form a soluble glass that wraps the V2O5 in the vanadium slag, reducing the V conversion rate. At the same time, the chemical stability of the vanadium slag spinel is relatively high, so that the crystal structure of the central part of the vanadium-containing spinel can be preserved relatively intact under roasting conditions. However, the relatively intact crystal structure will restrict the soluble conversion of part of the V2O3 in the crystal, that is, excessive calcium, silicon and chromium will cause the roasted material obtained by roasting to have a poor vanadium dissolution effect, which is not conducive to vanadium recovery. Based on this, the present invention improves the roasting process, and quickly cools the roasted material after heat preservation to obtain the roasted material, avoiding the defect that calcium, silicon and chromium form stable crystals with vanadium, which is not conducive to vanadium leaching. The specific details are as follows:

[0028] This embodiment provides a method for roasting vanadium slag, the roasting method comprising:

[0029] The vanadium slag and the sodium salt are mixed and then roasted to obtain a roasted material.

[0030] The vanadium slag comprises, by mass percentage, the following: Ca 2.5-4%, Cr 9-15%, Si 12-17%, Fe 3-5%, and V 11.5-14.5%.

[0031] In the present invention, the mass percentage of Ca in the vanadium slag is 2.5-4%, for example, it can be 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9% or 4%, etc., but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0032] In the present invention, the Cr content in the vanadium slag is 9-15% by mass, for example, it can be 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5% or 15%, etc., but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0033] In the present invention, the Si content in the vanadium slag is 12-17% by mass, for example, it can be 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5% or 17%, etc., but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0034] In the present invention, the Fe content in the vanadium slag is 3-5% by mass, for example, it can be 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8% or 5%, etc., but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0035] In the present invention, the V content in the vanadium slag is 11.5-14.5% by mass, for example, it can be 11.5%, 12%, 12.5%, 13%, 13.5%, 14% or 14.5%, etc., but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0036] In the present invention, the vanadium slag comes from the vanadium slag obtained by vanadium extraction in a converter. Other sources of vanadium slag that meet the requirements of limited elements, such as leaching slag, roasting slag, solid waste slag, waste catalyst and other materials, can also be selected to carry out the roasting process of the present invention.

[0037] The D85 particle size of the vanadium slag is 0.05-0.2 mm, for example, it can be 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm or 0.2 mm, etc., but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0038] Wherein, the sodium salt includes: sodium carbonate.

[0039] In the present invention, other salts such as sodium chloride, sodium sulfate, etc. can be introduced into the sodium salt for auxiliary roasting to further improve the final roasting effect.

[0040] The mass ratio of sodium salt to vanadium in the mixed material calculated as vanadium pentoxide is (1.3-1.5):1, for example, it can be 1.3:1, 1.32:1, 1.34:1, 1.36:1, 1.38:1, 1.4:1, 1.42:1, 1.44:1, 1.46:1, 1.48:1 or 1.5:1, but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0041] The roasting process includes: heat preservation and cooling in sequence.

[0042] The insulation temperature is 800-900°C, for example, it can be 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C or 900°C, but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0043] The insulation time is 2-2.5h, for example, 2h, 2.05h, 2.1h, 2.15h, 2.2h, 2.25h, 2.3h, 2.35h, 2.4h, 2.45h or 2.5h, but is not limited to the listed values. Other values not listed within the range also meet the requirements.

[0044] In the present invention, the calcination process is carried out under an oxidizing atmosphere such as oxygen or air.

[0045] In the present invention, the starting temperature for cooling is the temperature for keeping warm.

[0046] The cooling rate is ≥40°C / min, for example, it can be 40°C / min, 42°C / min, 44°C / min, 46°C / min, 48°C / min, 50°C / min, 52°C / min, 54°C / min, 56°C / min, 58°C / min or 60°C / min, but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0047] The temperature of the material obtained by cooling is 100-300°C, for example, it can be 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, 220°C, 240°C, 260°C, 280°C or 300°C, but is not limited to the listed values. Other values not listed within this range also meet the requirements.

[0048] In the present invention, the roasting process can be carried out in a rotary kiln, a roasting furnace, or other commonly used roasting equipment in the art. When roasting in a rotary kiln, the requirements of the holding time and the cooling rate are met by specifically controlling the process parameters of the rotary kiln, such as controlling parameters such as the kiln speed and air volume, and performing ventilation and kiln section cooling operations after the end of the holding period for rapid cooling.

[0049] The roasted material is immersed in water to obtain an leaching solution.

[0050] In the present invention, the ratio of the roasting material and water in the water immersion can be reasonably selected according to the requirements of the leaching solution.

[0051] The leaching solution is subjected to ammonium salt precipitation to recover vanadium elements.

[0052] In the present invention, ammonium salt precipitation of vanadium utilizes the solubility characteristics of ammonium vanadate. By adjusting the pH and temperature of the solution, vanadium is precipitated in the form of ammonium vanadate, and a high-purity vanadium compound is finally obtained. The specific pH value can be adjusted by ammonia water and / or ammonium salt.

[0053] The leached residue obtained from the water leaching is returned for roasting.

[0054] Furthermore, in order to illustrate that the roasted material obtained by the roasting method provided by the present invention can have a good vanadium dissolution effect, the following actual examples are used for illustration, as follows:

[0055] Example 1

[0056] This embodiment provides a method for roasting vanadium slag, which is as follows:

[0057] The vanadium slag and sodium carbonate are mixed and then roasted to obtain a roasted material.

[0058] The D85 particle size of the vanadium slag is 1.5 mm, and the mass percentage includes: Ca 3%, Cr 12%, Si 14%, Fe 4%, V 12%;

[0059] The mass ratio of sodium salt to vanadium in the mixed material calculated as vanadium pentoxide is 1.4:1;

[0060] The calcination comprises: sequentially carrying out heat preservation and cooling; the heat preservation temperature is 850°C for 2.2 hours; the temperature of the material obtained by cooling is 200°C at a cooling rate of 40°C / min;

[0061] The obtained roasted material is leached in water to obtain a leachate.

[0062] Example 2

[0063] This embodiment provides a method for roasting vanadium slag, which is as follows:

[0064] The vanadium slag and sodium carbonate are mixed and then roasted to obtain a roasted material.

[0065] The vanadium slag has a D85 particle size of 1 mm and comprises, by mass percentage, the following: Ca 3.5%, Cr 10%, Si 15%, Fe 4.5%, and V 13%;

[0066] The mass ratio of sodium salt to vanadium in the mixed material calculated as vanadium pentoxide is 1.45:1;

[0067] The calcination comprises: sequentially carrying out heat preservation and cooling; the heat preservation temperature is 880°C for 2.4 hours; the temperature of the material obtained by cooling is 250°C at a cooling rate of 50°C / min;

[0068] The obtained roasted material is leached in water to obtain a leachate.

[0069] Example 3

[0070] This embodiment provides a method for roasting vanadium slag, which is as follows:

[0071] The vanadium slag and sodium carbonate are mixed and then roasted to obtain a roasted material.

[0072] The D85 particle size of the vanadium slag is 0.05 mm, and the mass percentage includes: Ca 2.5%, Cr 15%, Si 12%, Fe 5%, and V 11.5%;

[0073] The mass ratio of sodium salt to vanadium in the mixed material calculated as vanadium pentoxide is 1.3:1;

[0074] The calcination comprises: sequentially carrying out heat preservation and cooling; the heat preservation temperature is 800°C and the time is 2.5 hours; the temperature of the material obtained by cooling is 100°C and the cooling rate is 60°C / min;

[0075] The obtained roasted material is leached in water to obtain a leachate.

[0076] Example 4

[0077] This embodiment provides a method for roasting vanadium slag, which is as follows:

[0078] The vanadium slag and sodium carbonate are mixed and then roasted to obtain a roasted material.

[0079] The vanadium slag has a D85 particle size of 0.2 mm and comprises, by mass percentage, the following: Ca 4%, Cr 9%, Si 17%, Fe 3%, and V 14.5%;

[0080] The mass ratio of sodium salt to vanadium in the mixed material calculated as vanadium pentoxide is 1.5:1;

[0081] The calcination comprises: sequentially carrying out heat preservation and cooling; the heat preservation temperature is 900°C for 2 hours; the temperature of the material obtained by cooling is 300°C at a cooling rate of 40°C / min;

[0082] The obtained roasted material is leached in water to obtain a leachate.

[0083] Comparative Example 1

[0084] The only difference from Example 1 is that the temperature is not lowered after calcination, but furnace cooling is performed and then water immersion is performed.

[0085] Comparative Example 2

[0086] The only difference from Example 1 is that the cooling rate is 10° C. / min.

[0087] Comparative Example 3

[0088] The only difference from Example 1 is that the cooling rate is 20° C. / min.

[0089] Example 4

[0090] The only difference from Example 1 is that the mass ratio of sodium salt to vanadium calculated as vanadium pentoxide in the mixed material is 1.2:1.

[0091] Example 5

[0092] The only difference from Example 1 is that the mass ratio of sodium salt to vanadium calculated as vanadium pentoxide in the mixed material is 1.8:1.

[0093] Example 6

[0094] The only difference from Example 1 is that the insulation time is 1.5 h.

[0095] Example 7

[0096] The only difference from Example 1 is that the temperature of the material obtained by cooling is 280°C.

[0097] The conversion effect of the roasted materials obtained in the above examples and comparative examples was analyzed. The conversion rate was calculated as: water-soluble vanadium in the roasted material / total vanadium in the roasted material × 100%. Elemental analysis was performed to compare the leaching effect. The leaching rate was calculated as: vanadium in the leachate / total vanadium in the vanadium slag × 100%, as shown in Table 1 below.

[0098] Table 1

[0099] Conversion rate / % Leaching rate / % Example 1 90.5 92.4 Example 2 90.6 96.5 Example 3 90.4 93.6 Example 4 91.2 97.8 Comparative Example 1 78.2 79.6 Comparative Example 2 79.5 80.6 Comparative Example 3 81.7 82.3 Example 5 83.2 89.5 Example 6 82.3 82.7 Example 7 81.2 83.5

[0100] As shown in Table 1, the roasting method provided by the present invention avoids the defect of forming vanadium bronze in the roasted material and causing poor vanadium dissolution effect by specifically cooling the material after roasting. The conversion rate of vanadium in the vanadium slag can reach more than 90%.

[0101] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0102] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0103] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for roasting vanadium slag, characterized in that: The roasting method comprises: Mixing vanadium slag and sodium salt, and then roasting to obtain a roasted material; The roasting comprises: sequentially carrying out heat preservation and cooling; The cooling rate is ≥40°C / min.

2. The roasting method according to claim 1, wherein The vanadium slag comprises, by mass percentage, Ca 2.5-4%, Cr 9-15%, Si 12-17%, Fe 3-5%, and V 11.5-14.5%; Preferably, the D85 particle size of the vanadium slag is 0.05-0.2 mm.

3. The roasting method according to claim 1, wherein The sodium salt includes: sodium carbonate.

4. The roasting method according to claim 1, wherein The mass ratio of sodium salt to vanadium in the mixed material calculated as vanadium pentoxide is (1.3-1.5):

1.

5. The roasting method according to claim 1, wherein The insulation temperature is 800-900°C.

6. The roasting method according to claim 1, wherein The insulation time is 2-2.5h.

7. The roasting method according to claim 1, wherein The temperature of the material obtained by cooling is 100-300°C.

8. The roasting method according to claim 1, wherein The roasted material is leached in water to obtain a leachate.

9. The roasting method according to claim 8, wherein The leaching solution is subjected to ammonium salt precipitation to recover vanadium element.

10. The roasting method according to claim 8, wherein The leached residue obtained from the water leaching is returned for roasting.