WO2020259500A1

WO2020259500A1 - Method for clean vanadium extraction by carbonation leaching of vanadium slag

Info

Publication number: WO2020259500A1
Application number: PCT/CN2020/097742
Authority: WO
Inventors: 付自碧; 郭继科; 蒋霖; 伍珍秀
Original assignee: 攀钢集团研究院有限公司
Priority date: 2019-06-24
Filing date: 2020-06-23
Publication date: 2020-12-30
Also published as: CN110106344A

Abstract

The present invention relates to the technical field of vanadium hydrometallurgy, and specifically relates to a method for clean vanadium extraction by carbonation leaching of vanadium slag. The technical problem to be solved by the present invention is to provide a method for clean vanadium extraction by carbonation leaching of vanadium slag, capable of reducing solid waste and improving the vanadium precipitation rate. The method comprises the following steps: a. uniformly mixing vanadium slag with a calcium salt and firing the mixture to obtain a fired clinker; b. adding water, a sodium-containing carbonate, and an ammonium-containing carbonate to the fired clinker for leaching, and performing solid-liquid separation to obtain a leachate, the amount of the sodium-containing carbonate, calculated as Na, being 1.0-1.5 times of the molar ratio of vanadium in the fired clinker; and c. adding a desilicating agent to the leachate, performing solid-liquid separation to obtain a desilicated solution, precipitating vanadium, performing solid-liquid separation to obtain ammonium metavanadate and a vanadium-precipitated supernatant, and calcining the ammonium metavanadate to obtain vanadium oxide. The method of the present invention improves the vanadium precipitation rate, reduces the use of leaching agents, and greatly reduces the generation of solid waste.

Description

Clean vanadium extraction method by carbonation leaching of vanadium slag

Technical field

The invention belongs to the technical field of vanadium hydrometallurgy, and specifically relates to a method for clean vanadium extraction by carbonated leaching of vanadium slag.

Background technique

Vanadium slag is the main raw material for preparing vanadium oxide. The traditional production process is sodium roasting and water leaching to extract vanadium. In this vanadium extraction process, a vanadium extraction tailing slag containing about 6% of sodium oxide will be produced. The secondary utilization of vanadium extraction tailings is difficult, and the vanadium-chromium reduction filter cake and a large amount of solid waste sodium sulfate are difficult to handle, which poses a greater environmental hazard ; In the process of extracting vanadium, a large amount of sodium carbonate is consumed, and the process cost is relatively high. In order to reduce the production cost of vanadium oxide and eliminate the hidden dangers of environmental protection, a process idea of preparing vanadium oxide by calcification roasting-carbonation leaching of vanadium slag is proposed.

The doctoral dissertation of Chongqing University published by Xinsheng Li published "Research on the Mechanism of the Roasting-Leaching Reaction Process of High-Calcium Low-grade Vanadium Slag". The ratio of leaching liquid to solid is 10:1 (mL/g). The vanadium concentration of the leaching solution obtained by this method is low and the Na/V ratio is high, resulting in a low vanadium precipitation rate during the subsequent precipitation of ammonium metavanadate.

Patent document CN102560086A discloses a method for extracting vanadium from ammonium carbonate leaching vanadium slag clinker. The method uses 200-800g/L ammonium carbonate solution and vanadium slag clinker at a liquid-solid ratio of 5:1-30:1 at 60～ The leaching was performed at 98°C. The leaching agent used in this method consumes a large amount and the production cost is high; and, due to the low solubility of ammonium metavanadate, in order to avoid the precipitation of vanadium into the residue in the form of ammonium metavanadate, the method needs to be controlled when leaching with ammonium carbonate. Large liquid-to-solid ratio, therefore, the concentration of vanadium in the leachate is low; on the other hand, the solubility of ammonium metavanadate decreases with the decrease of temperature. When the temperature of the leaching solution is lowered, ammonium metavanadate is easily precipitated, which leads to poor solution system. stable.

Summary of the invention

The technical problem to be solved by the present invention is to provide a clean vanadium extraction method by carbonation leaching of vanadium slag that can reduce solid waste and increase the rate of vanadium precipitation.

The technical solution adopted by the present invention to solve the above technical problems is to provide a clean vanadium extraction method by carbonation leaching of vanadium slag, which includes the following steps:

a. Mix and roast vanadium slag and calcium salt to obtain roasted clinker;

b. Add water, sodium carbonate and ammonium carbonate to the roasted clinker for leaching, and solid-liquid separation to obtain the leaching solution; the amount of sodium carbonate is calculated as Na as 1.0 to 1.0 of the molar amount of vanadium in the roasted clinker. 1.5 times; the amount of ammonium carbonate is 1.5 to 2.5 times the molar amount of vanadium in the roasted clinker calculated as CO ₃ ^2- ;

c. Adding a silicon removal agent to the leaching solution, solid-liquid separation to obtain a silicon-removed solution, precipitation of vanadium, solid-liquid separation to obtain ammonium metavanadate and vanadium precipitation supernatant, calcining the ammonium metavanadate to obtain vanadium pentoxide.

Wherein, in the above-mentioned vanadium slag carbonation leaching clean vanadium extraction method, step a meets at least one of the following:

The particle size of the vanadium slag is less than 0.096 mm.

The amount of the calcium salt is 0%-8% of the mass of the vanadium slag as CaO.

The calcium salt is at least one of calcium carbonate, calcium hydroxide, and calcium oxide.

The conditions of the firing are firing at 800-950°C for 40-200 min.

Wherein, in the above-mentioned vanadium residue carbonation leaching clean vanadium extraction method, in step b, the sodium carbonate is at least one of sodium carbonate and sodium bicarbonate.

Preferably, the sodium carbonate is sodium bicarbonate.

Further, in step b, the ammonium-containing carbonate is at least one of ammonium carbonate and ammonium bicarbonate. Preferably,

The ammonium-containing carbonate is ammonium bicarbonate.

Further, in step b, the temperature of the leaching is 80-100°C; the time of the leaching is 90-150 min.

Further, in step b, the solid ratio of the leachate is controlled at 1.8-2.5:1; the unit of the solid ratio of the leachate is mL:g.

Wherein, in the above-mentioned vanadium slag carbonation leaching clean vanadium extraction method, in step c, the silicon removing agent is sodium aluminate; the amount of sodium aluminate is that the molar ratio of Al/Si is 0.5 to 1.0; The vanadium is ammonium bicarbonate or ammonium carbonate, and the molar ratio of NH ₄ ⁺ /V is controlled to be 0.9-2.0.

Further, in step c, the solution after silicon removal is returned to the leaching step to absorb the ammonia and carbon dioxide that escaped during the leaching process, and then vanadium is deposited.

Further, in step c, the pH of the upper layer liquid of the vanadium precipitation is controlled to be 9.0-9.6.

Further, in step c, the vanadium precipitation upper layer liquid is returned to the leaching step as a leaching agent for recycling.

The vanadium slag in the present invention is an ordinary vanadium slag or a high-calcium and high-phosphorus vanadium slag obtained by oxidizing vanadium-containing molten iron.

The beneficial effects of the present invention are:

The method of the present invention uses a mixture of ammonium carbonate and sodium carbonate to extract the roasted clinker, and obtains a low-sodium leaching solution by controlling the amount of sodium salt, which is convenient to increase the vanadium precipitation rate, and the vanadium precipitation rate can reach more than 90% . The method of the invention obtains a high-concentration vanadium-containing leaching solution by controlling the leaching liquid-solid ratio and the leaching temperature, avoids the precipitation of ammonium metavanadate, and improves the stability of the solution system. The method of the present invention utilizes the ammonia released during the leaching process to be absorbed by the solution after silicon removal to realize the recycling of the ammonia medium, reduce the consumption of ammonium bicarbonate in the vanadium precipitation process, and avoid environmental pollution. The method of the present invention does not produce vanadium-chromium reduction filter cake and solid waste sodium sulfate, and the obtained vanadium precipitation upper layer liquid can be returned to the leaching process as a leaching agent for recycling, which realizes the low-cost and clean production of vanadium oxide from vanadium slag and reduces the cost of the leaching agent. Consumption solves the problems of high process cost of traditional vanadium slag sodium roasting-water leaching vanadium extraction, solid waste tailings, vanadium-chromium reduction filter cake, and difficult utilization of sodium sulfate.

Detailed ways

The raw materials and equipment used in the specific embodiments of the present invention are all known products and are obtained by purchasing commercially available products.

The invention provides a clean vanadium extraction method by carbonation leaching of vanadium slag, which includes the following steps:

a. Mix and roast vanadium slag and calcium salt to obtain roasted clinker;

In step a of the present invention, the vanadium slag used is ordinary vanadium slag or high-calcium and high-phosphorus vanadium slag obtained by oxidizing vanadium-containing molten iron. In order to fully expose the vanadium-iron spinel in the vanadium slag, facilitate the oxidation of the vanadium-iron spinel, and also facilitate the full contact reaction between the vanadium slag and the calcium salt, the vanadium slag is crushed, and the vanadium slag with a particle size of less than 0.096 mm is selected. Since the solubility of calcium metavanadate in water is greater than that of calcium pyrovanadate and calcium orthovanadate, it is beneficial to leaching. In order to control the vanadium in the calcified roasting clinker to be mainly in the form of calcium metavanadate, the amount of calcium salt added is CaO Calculated as 0%-8% of the mass of vanadium slag.

In step b of the present invention, the roasting clinker is mixed with sodium carbonate and ammonium carbonate as the leaching agent. On the one hand, ammonium carbonate or ammonium bicarbonate provides carbonate and calcium ions to react to form calcium carbonate. The solubility of calcium is lower than that of calcium metavanadate, calcium pyrovanadate and calcium orthovanadate. The generated calcium carbonate enters the slag, causing vanadium to enter the solution; on the other hand, ammonium carbonate and ammonium bicarbonate are heated to decompose to form ammonia, thereby achieving ammonia The separation from sodium allows ammonia to escape from the solution, creating conditions for the stable existence of high-concentration vanadium solutions. In addition, the inventors reduced the concentration of sodium in the solution by controlling the amount of sodium-containing carbonate to Na/V=1.0-1.5 (molar ratio), facilitating the subsequent precipitation of ammonium metavanadate, and facilitating the improvement of the vanadium precipitation rate. In order to further obtain a high-concentration vanadium-containing leaching solution, which is conducive to the precipitation of ammonium metavanadate, the inventors controlled the leaching solution-solid ratio at 1.8-2.5:1 (mL:g). In step b of the present invention, in order to facilitate the dissolution of calcium metavanadate, the leaching temperature is controlled at 80-100°C, and at the same time, it is beneficial for ammonia gas to escape from the solution, avoiding the precipitation of ammonium metavanadate, and improving the stability of the solution system. Sex.

In step c of the present invention, the solution after silicon removal is returned to the leaching step to absorb the ammonia and carbon dioxide that escaped during the leaching process, thereby realizing the recycling of ammonia medium, reducing the amount of ammonium bicarbonate in the vanadium precipitation process, and avoiding environmental Pollution. The obtained vanadium precipitation upper layer liquid mainly contains sodium carbonate, ammonium carbonate and a small amount of sodium vanadate. It can be directly returned to the leaching step as a leaching agent for leaching and roasting clinker for recycling. When using the vanadium precipitation upper layer liquid for cyclic leaching, add sodium salt appropriately according to the sodium concentration It satisfies Na/V=1.0～1.5 (molar ratio), reducing the amount of leaching agent. In the present invention, precipitation of ammonium metavanadate, vanadium precipitation to control the supernatant pH = 9.0 ~ 9.6 in order to control the vanadium precipitation liquid HCO ₃ ^- concentration, avoiding precipitation in the form of sodium bicarbonate.

In step c of the present invention, ammonium metavanadate is oxidized and calcined to obtain vanadium pentoxide.

Hereinafter, the present invention will be further described in detail through specific embodiments.

Example 1

Take 100g of vanadium slag (containing V ₂ O ₅ 17.2%, CaO 1.84%, P 0.04%) with a particle size of less than 0.096mm, and roast it in a muffle furnace at a roasting temperature of 950°C and air flow for 40 minutes to obtain roasted clinker; The roasted clinker is crushed and added to 200mL of water. At the same time, 23.6g of sodium bicarbonate and 25.3g of ammonium bicarbonate are added, and the slurry is stirred and leached for 120 minutes at a slurry temperature of 95°C. The leaching liquid-to-solid ratio is 2:1. The solid-liquid separation obtains the leaching liquid. And the residue, the residue TV is 0.92wt% and Na0.39%, and the vanadium leaching rate is 90.3%; 0.8g sodium aluminate is added to the leaching solution, stirred for 20 minutes, and filtered to obtain the silicon-removed solution; the silicon-removed solution is cooled to 15℃, Under stirring, add 32g ammonium bicarbonate precipitation reaction for 180min, solid-liquid separation, obtain ammonium metavanadate and vanadium precipitation supernatant; Vanadium precipitation supernatant TV 3.94g/L; ammonium metavanadate oxidized and calcined at 500℃ for 5h, The V ₂ O ₅ content of the obtained sample was 98.9%. The vanadium deposition rate is 90.94%.

The vanadium precipitation upper layer liquid is used as a leaching agent for the next round of leaching. Sodium carbonate or sodium bicarbonate is appropriately added during leaching to meet the control requirements of Na/V = 1.0 to 1.5 (molar ratio); ammonium salt does not need to be added.

Example 2

Take 100g of vanadium slag (containing V ₂ O ₅ 17.2%, CaO 1.84%, P 0.04%) with a particle size of less than 0.096mm and mix it with 3g of calcium oxide uniformly, and roast for 80 minutes in a muffle furnace at a roasting temperature of 900℃ and air ; The roasted clinker is crushed and added to 250mL of water. At the same time, 19.5g of sodium carbonate and 30.8g of ammonium bicarbonate are added, and the slurry is leached for 150min under the condition of slurry temperature 100℃. The leaching liquid-solid ratio is 2.5:1. Vanadium leaching solution and residue, residue TV 1.06wt% and Na 0.34%, the vanadium conversion leaching rate is 88.8%; add 0.7g sodium aluminate to the leaching solution, stir for 20min and filter to obtain the silicon-removed solution; return the silicon-removed solution to the leaching step Absorb the ammonia and carbon dioxide that escaped during the leaching process, then cool the solution after silicon removal to 18°C, add 30g of ammonium bicarbonate to precipitate the reaction for 180 minutes while stirring, and separate solid and liquid to obtain ammonium metavanadate and vanadium precipitation supernatant , Vanadium precipitation upper liquid TV 3.14g/L; ammonium metavanadate was oxidized and calcined at 500°C for 5h, and the sample obtained had a V ₂ O ₅ content of 98.7%. The vanadium deposition rate is 90.82%.

Example 3

Take 100g of vanadium slag (containing V ₂ O ₅ 17.2%, CaO 1.84%, P 0.04%) with a particle size of less than 0.096mm and mix it with 8g of calcium oxide uniformly, and roast for 180 minutes in a muffle furnace at a roasting temperature of 850℃ and air ; The roasted clinker is crushed and added to 250mL of water, while adding 17.8g of sodium carbonate and 37.2g of ammonium bicarbonate, stirring and leaching for 100min under the condition of the slurry temperature of 85℃, the leaching liquid-solid ratio is 2.3:1, the solid-liquid separation obtains the leaching liquid And the residue, the residue TV 1.02wt% and Na 0.37%, the vanadium leaching rate is 89.4%; add 0.7g sodium aluminate to the leaching solution, stir for 20min and then filter to obtain the silicon-removed solution; return the silicon-removed solution to the leaching step for absorption and leaching Ammonia and carbon dioxide escaped during the process, then the solution after silicon removal was cooled to 20°C, 30g of ammonium bicarbonate was added under stirring, and the precipitation was reacted for 180 minutes, and the solid-liquid separation was carried out to obtain ammonium metavanadate and vanadium precipitation supernatant. Vanadium supernatant liquid TV 3.34g/L; ammonium metavanadate was oxidized and calcined at 500°C for 5h, and the sample obtained had a V ₂ O ₅ content of 98.9%. The vanadium deposition rate is 90.31%.

In summary, the method of the present invention is used to obtain a low sodium content leaching solution by controlling the amount of sodium salt, which improves the vanadium transfer rate and the vanadium precipitation rate, so that the vanadium precipitation rate is 90.31% to 90.94%. The method of the present invention does not produce vanadium-chromium reduction filter cake and solid waste sodium sulfate, and the obtained vanadium precipitation upper layer liquid can be returned to the leaching process as a leaching agent for recycling, which realizes the low-cost and clean production of vanadium oxide from vanadium slag and reduces the cost of the leaching agent. Consumption solves the problems of high process cost of traditional vanadium slag sodium roasting-water leaching vanadium extraction, solid waste tailings, vanadium-chromium reduction filter cake, and difficult utilization of sodium sulfate.

Claims

The clean vanadium extraction method by carbonation leaching of vanadium slag is characterized in that it comprises the following steps:

a. Mix and roast vanadium slag and calcium salt to obtain roasted clinker;

b. Add water, sodium carbonate and ammonium carbonate to the roasted clinker for leaching, and solid-liquid separation to obtain the leaching solution; the amount of sodium carbonate is calculated as Na as 1.0 to 1.0 of the molar amount of vanadium in the roasted clinker. 1.5 times; the amount of ammonium carbonate is 1.5 to 2.5 times the molar amount of vanadium in the roasted clinker calculated as CO 3 2- ;

c. Adding a silicon removal agent to the leaching solution, solid-liquid separation to obtain a silicon-removed solution, precipitation of vanadium, solid-liquid separation to obtain ammonium metavanadate and vanadium precipitation supernatant, calcining the ammonium metavanadate to obtain vanadium pentoxide.
The method for cleaning vanadium extraction by carbonation leaching of vanadium slag according to claim 1, wherein at least one of the following is satisfied in step a:

The particle size of the vanadium slag is less than 0.096 mm;

The dosage of the calcium salt is 0%-8% of the mass of the vanadium slag as CaO;

The calcium salt is at least one of calcium carbonate, calcium hydroxide, and calcium oxide;

The conditions of the firing are firing at 800-950°C for 40-200 min.
The clean vanadium extraction method by carbonation leaching of vanadium slag according to claim 1 or 2, characterized in that: in step b, the sodium carbonate is at least one of sodium carbonate and sodium bicarbonate; preferably, The sodium carbonate is sodium bicarbonate.
The clean vanadium extraction method by carbonation leaching of vanadium slag according to any one of claims 1 to 3, characterized in that: in step b, the ammonium-containing carbonate is at least one of ammonium carbonate and ammonium bicarbonate; Preferably, the ammonium-containing carbonate is ammonium bicarbonate.
The clean vanadium extraction method by carbonation leaching of vanadium slag according to any one of claims 1 to 4, characterized in that: in step b, the temperature of the leaching is 80-100°C; and the time of leaching is 90-150 min.
The method for clean vanadium extraction by carbonation leaching of vanadium slag according to any one of claims 1 to 5, characterized in that: in step b, the solid ratio of the leaching liquid is controlled to be 1.8 to 2.5:1.
The method for cleaning vanadium extraction by carbonation leaching of vanadium slag according to any one of claims 1 to 6, characterized in that: in step c, the silicon removing agent is sodium aluminate; the amount of sodium aluminate is Al/ The molar ratio of Si is 0.5 to 1.0; the vanadium precipitation is ammonium bicarbonate or ammonium carbonate, and the molar ratio of NH 4 + /V is controlled to be 0.9 to 2.0.
The clean vanadium extraction method by carbonation leaching of vanadium slag according to any one of claims 1 to 7, characterized in that: in step c, the solution after silicon removal is returned to the leaching step to absorb ammonia and carbon dioxide that escaped during the leaching process. Then sink vanadium.
The clean vanadium extraction method by carbonation leaching of vanadium slag according to any one of claims 1 to 8, characterized in that: in step c, the pH of the vanadium precipitation upper layer liquid is controlled to be 9.0 to 9.6.
The method for cleaning vanadium extraction by carbonation leaching of vanadium slag according to any one of claims 1 to 9, characterized in that: in step c, the vanadium precipitation upper layer liquid is returned to the leaching step as a leaching agent for recycling.