A method for extracting vanadium by alkaline oxidation and low-temperature calcination from vanadium chloride slag produced by a high-titanium slag chlorination system

Abstract

The application provides a method for extracting vanadium from chlorinated vanadium slag by alkaline oxidation and low-temperature calcination, and belongs to the technical field of metallurgy. The method comprises the following steps: uniformly mixing the chlorinated vanadium slag and sodium hypochlorite, adding sodium hydroxide solution, stirring and reacting at 50-70 DEG C for 60-120 min; the sodium hypochlorite oxidizes low-valence vanadium in the slag into pentavalent vanadium and dissolves in the sodium hydroxide solution, realizing the separation of vanadium from impurities such as titanium; adding an ammonium salt into the vanadium-containing filtrate to obtain ammonium vanadate by precipitation; and preparing vanadium pentoxide products by filtering and low-temperature calcination. The sodium hydroxide and a small amount of sodium hypochlorite in the filtrate can be recycled. The application avoids the traditional high-temperature sodium calcination process, has a short process flow and low energy consumption, the obtained vanadium pentoxide has a purity greater than 99%, the by-product titanium slag can be reused in the titanium smelting system, and has a wide industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for alkaline oxidation-low-temperature calcination to extract vanadium from vanadium chloride slag produced by a high-titanium slag chlorination system. Background Technology

[0002] Vanadium is an important strategic metal with wide applications and is difficult to replace. Currently, primary vanadium resources at home and abroad are gradually being depleted, and secondary resources have become the main source of vanadium. Traditional sodium roasting and calcification roasting processes for vanadium extraction both require a roasting step, which has problems such as high energy consumption, generation of harmful gases such as chlorine and hydrogen chloride, high environmental pollution risks, stringent equipment requirements, and poor operating environment, and does not conform to the concept of low-carbon, green and sustainable development.

[0003] Current technology typically involves converting vanadium in vanadium slag into sodium vanadate at a high temperature of around 800℃ using oxygen and sodium salts. After dissolution and separation, ammonium salts are added to precipitate the vanadium, which is then dried and roasted to obtain vanadium pentoxide. This method still requires heating to approximately 800℃, resulting in high energy consumption, and also produces harmful gases such as chlorine and hydrogen chloride.

[0004] To address the technical bottlenecks of existing vanadium extraction processes, such as high energy consumption and significant pollution, this invention proposes a method for vanadium extraction from vanadium chloride slag through alkaline oxidation followed by low-temperature calcination. This method eliminates the need for a roasting process to produce vanadium pentoxide, allows for the recycling of sodium hydroxide, and enables the production of titanium slag for reuse in titanium smelting systems. This method is characterized by its cleanliness, high efficiency, and low energy consumption. Summary of the Invention

[0005] This invention utilizes alkaline oxidation-low-temperature calcination of vanadium chloride slag to extract vanadium, solving the problems of high energy consumption and significant environmental pollution associated with traditional smelting methods in the background.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: The method for vanadium extraction using alkaline oxidation-low-temperature calcination of vanadium chloride slag includes the following steps: (1) Mix vanadium slag, water and sodium hypochlorite, then heat and stir to oxidize; (2) Add sodium hydroxide solid to the solution from step (1) for alkaline washing; (3) Filter the solution from step (2) to obtain leachate and titanium slag. The titanium slag can be returned to the production line of Longbai Lufeng Titanium Industry Co., Ltd. for comprehensive utilization. (4) Add ammonium salt to the leachate from step (3), filter to obtain ammonium metavanadate and a reusable aqueous solution containing sodium hydroxide; (5) Calcining the ammonium metavanadate from step (4) at low temperature to obtain vanadium pentoxide.

[0007] The oxidation process includes: mixing vanadium slag and sodium hypochlorite and placing them in a beaker, dissolving them with sodium hydroxide, first turning on a constant temperature magnetic stirrer, waiting for the temperature to rise to 40-70℃, placing the beaker in it, stirring at a rate of 200-400 r / min, and keeping it at that temperature for 60-180 min.

[0008] The mixing ratio in step (1) is a mass ratio of 1:0.2 to 1:0.4 and a solid-liquid ratio of 1:2 to 1:5.

[0009] The mass ratio of sodium hydroxide to vanadium slag in step (2) is 1:0.5 to 1:2.

[0010] The liquid-solid separation in step (3) can be achieved by conventional vacuum filtration.

[0011] The precipitation temperature in step (4) is 50-70℃, the precipitation time is 30-120 min, and the ammonium salt can be ammonium chloride, ammonium sulfate, ammonium carbonate, etc. The low-temperature calcination in step (5) is carried out at a temperature of 300-500°C for 30-60 minutes.

[0012] The results of the examples show that the vanadium pentoxide extraction technology using alkaline oxidation-low temperature calcination of vanadium chloride slag adopted in this invention has a direct vanadium recovery rate of more than 80% and a vanadium pentoxide purity of more than 99%, thus producing vanadium pentoxide from vanadium slag. Attached Figure Description

[0013] Figure 1 This is a process flow diagram of the present invention; Figure 2 Image of vanadium pentoxide; Figure 3 The image shows the XRD pattern of vanadium pentoxide. Detailed Implementation

[0014] To make the objectives, technical solutions, and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below to facilitate understanding by those skilled in the art. Example 1

[0015] The method for vanadium extraction from vanadium chloride slag through alkaline oxidation and low-temperature calcination is as follows: Figure 1As shown, the specific steps are as follows: (1) Mix 30g of dried vanadium slag with 90ml of pure water and 6g of sodium hypochlorite with a purity of 99%, and heat and stir at 50℃ for 60min at a stirring rate of 200r / min; (2) Leach 20g of sodium hydroxide solid into the above solution with alkali; (3) Filter the solution from the previous step to obtain leachate and titanium slag. The titanium slag can be returned to the production line of Longbai Lufeng Titanium Industry Co., Ltd. for comprehensive utilization; (4) Add 10g of ammonium chloride to the leachate, precipitate at 50℃ for 60min, and filter to obtain ammonium metavanadate and a reusable sodium hydroxide aqueous solution; (5) Place the ammonium metavanadate into a low-temperature calcining furnace and start heating at a rate of 5℃ / min. After the displayed temperature reaches 450℃, keep it at that temperature for 1h to obtain solid vanadium pentoxide. The direct recovery rate of vanadium is 87.54%, and the purity of the vanadium pentoxide product is 99.20%. The actual picture of the prepared vanadium pentoxide is shown in the figure. Figure 2 As shown, the XRD pattern of vanadium pentoxide is as follows. Figure 3 As shown. Example 2

[0016] The method for vanadium extraction from vanadium chloride slag through alkaline oxidation and low-temperature calcination is as follows: Figure 1 As shown, the specific steps are as follows: (1) Mix 20g of dried vanadium slag with 60ml of pure water and 5g of sodium hypochlorite with a purity of 99%, and heat and stir at 70℃ for 100min and 300r / min; (2) Leach 25g of sodium hydroxide solid into the above solution with alkali; (3) Filter the solution from the previous step to obtain leachate and titanium slag. The titanium slag can be returned to the production line of Longbai Lufeng Titanium Industry Co., Ltd. for comprehensive utilization; (4) Add 12g of ammonium carbonate to the leachate, precipitate at 60℃ for 100min, filter to obtain ammonium metavanadate and a reusable sodium hydroxide aqueous solution; (5) Place the ammonium metavanadate into a low-temperature furnace. After the pressure in the furnace drops to 15Pa, start heating at a rate of 5℃ / min. After the displayed temperature reaches 400℃, keep it at that temperature for 1.5h to obtain solid vanadium pentoxide. The direct recovery rate of vanadium is 88.23%, and the purity of the vanadium pentoxide product is 99.15%. Example 3

[0017] The method for vanadium extraction from vanadium chloride slag through alkaline oxidation and low-temperature calcination is as follows: Figure 1As shown, the specific steps are as follows: (1) Mix 50g of dried vanadium slag with 200ml of pure water and 10g of sodium hypochlorite with a purity of 99%, and heat and stir at 60℃ for 180min and 350r / min; (2) Leach 50g of sodium hydroxide solid into the above solution with alkali; (3) Filter the solution from the previous step to obtain leachate and titanium slag. The titanium slag can be returned to the production line of Longbai Lufeng Titanium Industry Co., Ltd. for comprehensive utilization; (4) Add 20g of ammonium sulfate to the leachate, precipitate at 70℃ for 50min, and filter to obtain ammonium metavanadate and a reusable sodium hydroxide aqueous solution; (5) Place the ammonium metavanadate into a low-temperature furnace. After the pressure in the furnace drops to 5Pa, start heating at a rate of 5℃ / min. After the displayed temperature reaches 500℃, keep it at that temperature for 1h to obtain solid vanadium pentoxide. The direct recovery rate of vanadium is 90.23%, and the purity of the vanadium pentoxide product is 99.32%.

[0018] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the invention in any specific way. Therefore, any modifications and improvements to the present invention are considered to be within the scope of protection of the present invention.

Claims

1. A method for alkaline oxidation-low-temperature calcination to extract vanadium from vanadium chloride slag produced by a high-titanium slag chlorination system, characterized in that, Includes the following steps: (1) Mix vanadium slag, water and sodium hypochlorite, then heat and stir to oxidize; (2) Add sodium hydroxide to the solution from step (1) and wash. (3) Filter the solution from step (2) to obtain leachate and titanium slag. The titanium slag can be returned to the titanium smelting system for comprehensive utilization. (4) Add ammonium salt to the leachate from step (3), filter to obtain ammonium metavanadate, and the sodium hydroxide aqueous solution can be returned to the alkaline washing step for reuse; (5) Calcining the ammonium metavanadate from step (4) at a low temperature of 400-500℃ to obtain vanadium pentoxide.

2. The method for vanadium extraction using alkaline oxidation-low-temperature calcination of vanadium chloride slag according to claim 1, characterized in that, The oxidation process includes: mixing vanadium slag, water and sodium hypochlorite in a beaker, then adding sodium hydroxide, turning on a constant temperature magnetic stirrer, and placing the beaker in the beaker when the temperature rises to 40~70℃, stirring at a rate of 200~400 r / min, and maintaining the temperature for 60min~180min.

3. The method for vanadium extraction using alkaline oxidation-low-temperature calcination of vanadium chloride slag according to claim 1, characterized in that... The mass ratio of vanadium slag and sodium hypochlorite in step (1) is 1:0.2~1:0.4, and the solid-liquid ratio is 1:2~1:

5.

4. The method for vanadium extraction using alkaline oxidation-low-temperature calcination of vanadium chloride slag according to claim 1, characterized in that... In step (2), the mass ratio of sodium hydroxide to vanadium slag is 1:0.5~1:

2.

5. The method for vanadium extraction using alkaline oxidation-low-temperature calcination of vanadium chloride slag according to claim 1, characterized in that... The liquid-solid separation in step (3) can be achieved by conventional vacuum filtration.

6. The method for vanadium extraction using alkaline oxidation-low-temperature calcination of vanadium chloride slag according to claim 1, characterized in that... The precipitation temperature in step (4) is 50-70℃ and the precipitation time is 30-120 min; the ammonium salt can be ammonium chloride, ammonium sulfate, ammonium carbonate, etc.

7. The method for vanadium extraction using alkaline oxidation-low-temperature calcination of vanadium chloride slag according to claim 1, characterized in that... Step (5) The low-temperature calcination temperature is 400-500℃ and the time is 30-60min.

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