A method for preparing vanadium pentoxide by using organic amine flue gas desulfurization residue

Abstract

The present application belongs to the field of waste resource utilization and hydrometallurgy, and particularly relates to a method for preparing vanadium pentoxide by using organic amine flue gas desulfurization residue, which adopts melamine method flue gas desulfurization residue as a vanadium precipitation agent. Under acidic conditions, the organic amine flue gas desulfurization residue can react with vanadate to generate more stable organic amine vanadate precipitate. After filtration, the precipitate is high-temperature calcined to obtain high-purity powder vanadium pentoxide. Compared with the current ammonium sulfate salt vanadium precipitation method, the present application has higher precipitable vanadium concentration, low ammonia nitrogen concentration in wastewater, and no need for heating in the reaction process, and is an environmentally friendly and low-cost vanadium pentoxide preparation technology.

Description

Technical Field

[0001] This invention belongs to the field of waste resource utilization and hydrometallurgical technology, specifically relating to a method for preparing vanadium pentoxide using organic amine flue gas desulfurization slag. Background Technology

[0002] Vanadium is a high-melting-point rare metal. Due to its excellent alloying properties and catalytic activity, it has become an important strategic resource, often referred to as a "metallic vitamin." Because vanadium is relatively dispersed in nature and often occurs as an associated mineral with other metals, it is usually recovered as a byproduct during the smelting of its associated metals. In the smelting of vanadium-titanium magnetite, vanadium-bearing iron ore is first smelted in a blast furnace or electric furnace to obtain vanadium-bearing molten iron. Then, based on the principle of selective oxidation in a converter, the vanadium element in the molten iron is preferentially oxidized to the maximum extent and enriched in the slag phase, resulting in slag with a high vanadium content, also known as vanadium slag. The vanadium slag is then mixed with sodium chloride, sodium carbonate, and return slag in a rotary kiln and roasted in a certain proportion, causing the vanadium in the vanadium slag to form water-soluble sodium salts. Subsequently, a countercurrent hot water leaching technique is used to transfer the soluble vanadium to the leaching solution, and calcium chloride is used to treat the vanadium solution for dephosphorization and desiliconization. Ammonium sulfate is added to the purified vanadium solution to adjust it to acidity and maintain the temperature above 90°C. This precipitates the soluble vanadium in the leachate as ammonium polyvanadate (APV). The precipitate is then calcined at high temperature to obtain vanadium pentoxide. Traditional ammonium salt precipitation technology for high-concentration vanadium leachates easily introduces impurities into the precipitate, leading to a decrease in the purity of the vanadium pentoxide product. Furthermore, a large amount of ammonia nitrogen remains in the wastewater, increasing the burden of subsequent water treatment and placing significant environmental pressure on enterprises.

[0003] Melamine can be used as a desulfurizing agent in organic amine flue gas desulfurization processes. Melamine reacts with SO2 in the flue gas to form melamine sulfite, thereby removing SO2 from the flue gas. Melamine sulfite can be regenerated by heating at 75-150℃. However, during the recirculation desulfurization process, the oxygen in the flue gas can oxidize some of the melamine sulfite into melamine sulfate, which is difficult to regenerate. This ultimately leads to the failure of the desulfurizing agent and the formation of waste residue mainly composed of melamine sulfite and melamine sulfate, limiting the practical application of this process. Summary of the Invention

[0004] This invention provides a method for preparing vanadium pentoxide using organic amine flue gas desulfurization slag. The method uses the organic amine flue gas desulfurization slag as a vanadium precipitant. Under acidic conditions, the pretreated organic amine flue gas desulfurization slag reacts with vanadate ions to form a more stable organic amine vanadate precipitate. The precipitate is filtered and then calcined at high temperature to obtain high-purity powdered vanadium pentoxide. Compared with the existing ammonium salt precipitation method, this invention achieves a higher precipitate concentration of vanadium, produces extremely low ammonia nitrogen emissions in wastewater, and requires no heating during the reaction process. It is an environmentally friendly and low-cost vanadium pentoxide production technology.

[0005] A method for preparing vanadium pentoxide from organic amine flue gas desulfurization slag, characterized by the following steps:

[0006] (1) Flue gas desulfurization residue pretreatment stage: Add a certain amount of organic amine flue gas desulfurization residue to water, the mass fraction of desulfurization residue is <40%, use sulfuric acid to adjust the solution to pH=1.0-4.0, stir for 10-30 min, filter and dehydrate after the reaction is completed, and dry at 80℃ for 2h;

[0007] (2) Vanadium precipitation stage: After adjusting the high concentration vanadium-containing solution to pH=1.0-3.0, a certain amount of treated desulfurization slag is added, and the mixture is stirred continuously at 20-90℃ for 10-60 min. The amount of desulfurization slag added is 0.5-1.5 times the mass of vanadium. After the reaction is completed, the precipitate is filtered and dehydrated, and then dried at 80℃ for 2 h.

[0008] (3) Oxidation roasting stage: The dried vanadium-containing precipitate is placed in a muffle furnace and roasted at 500-900℃ for 1.0-3.0h.

[0009] The organic amine flue gas desulfurization residue refers to the desulfurizing agent that has become ineffective after fully circulating and absorbing sulfur dioxide in the flue gas, using melamine as the desulfurizing agent. Its main components are melamine sulfite and melamine sulfate.

[0010] In the flue gas desulfurization slag pretreatment stage, the mass fraction of the flue gas desulfurization slag is less than 40%, and sulfuric acid is used to adjust the solution to pH=1.0-4.0.

[0011] In the vanadium precipitation stage, the high-concentration vanadium-containing solution comes from the water leaching vanadium extraction process, wherein the vanadium content is 20-100 g / L.

[0012] In the vanadium precipitation stage, the pH of the high-concentration vanadium-containing solution needs to be adjusted to 1.0-3.0 first, and then the desulfurization slag is added at 0.5-1.5 times the mass of vanadium. No further pH adjustment is needed during the stirring process.

[0013] The use of organic amine flue gas desulfurization residue avoids the problem of excessive melamine dosage leading to polymerization during the reaction and preventing precipitation separation when directly using melamine for vanadium precipitation. Compared with traditional ammonium salt vanadium precipitation, this process results in extremely low ammonia nitrogen emissions.

[0014] Compared with the prior art, the features and beneficial effects of the present invention are as follows:

[0015] Compared with the existing ammonium sulfate precipitation method, this invention can precipitate vanadium at a higher concentration, produces extremely low ammonia nitrogen in the wastewater, and requires no heating during the reaction process. It is an environmentally friendly and low-cost vanadium pentoxide preparation technology. Attached Figure Description

[0016] Figure 1 The XRD patterns of the desulfurization slag, vanadium-containing precipitate, and vanadium pentoxide after treatment in this embodiment of the invention are shown. Detailed Implementation

[0017] The methods and techniques described in this invention are illustrated below through examples, but in practical applications, they are not limited to these examples. Example

[0018] The method for preparing vanadium pentoxide using organic amine flue gas desulfurization residue described in this embodiment is carried out according to the following steps:

[0019] (1) Flue gas desulfurization residue pretreatment stage: 80g organic amine flue gas desulfurization residue was added to 150g water, the solution was adjusted to pH=2.0 with sulfuric acid, stirred for 15 min, filtered and dehydrated after the reaction was completed, and dried at 80℃ for 2h;

[0020] (2) Vanadium precipitation stage: Take 150 mL of high-concentration vanadium-containing solution with a vanadium content of 40 g / L, adjust the pH to 2.0 with sulfuric acid, add the treated desulfurization slag at 1.0 times the mass of vanadium, stir continuously at room temperature (20℃) for 20 min, filter and dehydrate the precipitate after the reaction is completed, and dry at 80℃ for 2 h.

[0021] (3) Oxidation roasting stage: The dried vanadium-containing precipitate is placed in a muffle furnace and roasted at 600℃ for 1.5h.

[0022] After vanadium precipitation, the residual vanadium concentration in the leachate was 0.013 g / L, the residual ammonia nitrogen concentration was 0.52 mg / L, and the purity of vanadium pentoxide after calcination was 98.6%. Example

[0023] The method for preparing vanadium pentoxide using organic amine flue gas desulfurization residue described in this embodiment is carried out according to the following steps:

[0024] (1) Flue gas desulfurization residue pretreatment stage: Add 80g organic amine flue gas desulfurization residue to 150g water, adjust the solution to pH=2.5 with sulfuric acid, stir for 15 min, filter and dehydrate after the reaction is completed, and dry at 80℃ for 2h;

[0025] (2) Vanadium precipitation stage: Take 150 mL of high-concentration vanadium-containing solution with a vanadium content of 80 g / L, adjust the pH to 2.5 with sulfuric acid, add the treated desulfurization slag at 1.2 times the mass of vanadium, stir continuously at 90℃ for 20 min, filter and dehydrate the precipitate after the reaction is completed, and dry at 80℃ for 2 h.

[0026] (3) Oxidation roasting stage: The dried vanadium-containing precipitate is placed in a muffle furnace and roasted at 600℃ for 1.5h.

[0027] After vanadium precipitation, the residual vanadium concentration in the leachate was 0.089 g / L, the residual ammonia nitrogen concentration was 0.73 mg / L, and the purity of vanadium pentoxide after calcination was 98.0%.

[0028] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing vanadium pentoxide from desulfurization residue of organic amine flue gas, characterized in that... Follow these steps: (1) Pretreatment stage of flue gas desulfurization residue: A certain amount of organic amine flue gas desulfurization residue is added to water, and the solution is adjusted to pH=1.0-4.0 with sulfuric acid. Stir for 10-30 min, filter and dehydrate after the reaction is completed, and dry at 80℃ for 2 h to obtain the treated desulfurization residue; The organic amine flue gas desulfurization residue refers to the desulfurizing agent that has been used as a desulfurizing agent and has become ineffective after fully circulating and absorbing sulfur dioxide in the flue gas. Its main components are melamine sulfite and melamine sulfate; (2) Vanadium precipitation stage: After adjusting the pH of the high-concentration vanadium-containing solution to 1.0-3.0, a certain amount of treated desulfurization slag is added, and the mixture is stirred continuously at 20-90℃ for 10-60 min. No further pH adjustment is required during the stirring process. The amount of desulfurization slag added is 0.5-1.5 times the mass of vanadium. After the reaction is completed, the precipitate is filtered and dehydrated, and then dried at 80℃ for 2 h. The high-concentration vanadium-containing solution is derived from the water leaching vanadium extraction process, and the vanadium content is 20-100 g / L. (3) Oxidation roasting stage: The dried vanadium-containing precipitate is placed in a muffle furnace and roasted at 500-900℃ for 1.0-3.0h.

2. The method for preparing vanadium pentoxide using organic amine flue gas desulfurization slag according to claim 1, characterized in that... In the flue gas desulfurization slag pretreatment stage, the desulfurization slag mass fraction is less than 40%, and sulfuric acid is used to adjust the solution to pH=1.0-4.0.

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