Converter vanadium slag grain size and crystallinity regulation and control low-temperature single-step sodium salt roasting vanadium extraction method

Abstract

The invention discloses a converter vanadium slag grain size and crystallinity regulation and control low-temperature single-step sodium salt roasting vanadium extraction method, and belongs to the technical field of rare metal metallurgy. According to the method, on the basis of a traditional two-step sodium salt roasting-water leaching vanadium extraction process, vanadium-containing converter slag is subjected to mechanical activation and granulation, pellet particles are subjected to low-temperature sodium salt roasting and then subjected to water leaching, vanadium is efficiently and fully leached into a solution, and associated macro elements such as iron, manganese and titanium are still left in the slag. According to the process, ore phase conversion of a vanadium carrier phase in the low-temperature single-step sodium salt roasting process is promoted, efficient vanadium extraction is ensured, and furnace body slagging is avoided. The single-step roasting process reduces the waste of energy and additives generated by traditional secondary roasting, improves the working environment, prevents the slagging phenomenon of the furnace body, reduces the consumption of ammonia-nitrogen wastewater in the subsequent vanadium precipitation process, ensures the smooth operation of the production process, and finally improves the production efficiency. The method has the characteristics of low energy consumption, less pollution and high comprehensive recovery rate, and meets the requirement of clean production.

Description

Technical Field

[0001] The present invention relates to the technical field of rare metal metallurgy, and particularly provides a method for regulating the crystal grain size and crystallinity of converter vanadium slag and extracting vanadium by low-temperature single-step sodium roasting, that is, a method for efficiently extracting vanadium by strengthening the low-temperature single-step sodium roasting-water leaching process through regulating the crystal grain size and crystallinity of converter vanadium slag. Background Art

[0002] Vanadium is a scarce resource, known as the "monosodium glutamate of modern industry", and rarely exists in the form of independent minerals. It is mainly hosted in vanadium-titanium magnetite and stone coal. Among them, 88% of the world's annual vanadium production is obtained from converter vanadium slag. Most of the vanadium in converter vanadium slag is hosted in spinel in the form of low-valence oxides. The vanadium extraction process from vanadium slag can be divided into two categories: roasting-assisted leaching and direct leaching. Due to the relatively stable chemical properties of spinel, it is extremely difficult to directly leach vanadium. Therefore, roasting-assisted leaching is the mainstream industrial vanadium extraction process, mainly including roasting, leaching, and precipitation processes. Roasting additives include sodium, calcium, magnesium, and mixed salts. Among them, sodium salt roasting is a mature method for extracting vanadium, with high recovery efficiency. This process involves the generation of Na2O through the high-temperature decomposition of sodium salt-containing substances such as Na2CO3, Na2SO3, and NaCl, and then the reaction of Na2O with V2O5 generated by the oxidation of the spinel phase to form water-soluble vanadate. This process successfully separates vanadium from associated elements such as silicon, iron, titanium, manganese, and magnesium.

[0003] However, a typical problem in the sodium salt roasting process is that when the roasting temperature is higher than 750 - 800 °C, the rotary kiln is prone to sintering and forming a ring, which will reduce the processing capacity of the kiln. In severe cases, it will hinder production. If the roasting temperature is reduced, the leaching rate of vanadium will decrease, and secondary roasting has to be carried out to improve the leaching rate of vanadium. Although the current sodium salt secondary roasting-water leaching process in the process avoids the formation of rings in the furnace and improves the vanadium leaching efficiency, it also greatly increases the consumption of energy and sodium salts, as well as the treatment cost of sodium-containing ammonia-nitrogen wastewater in the vanadium precipitation process, and reduces the production efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for regulating the crystal grain size and crystallinity of converter vanadium slag and extracting vanadium by low-temperature single-step sodium roasting, that is, a method for efficiently extracting vanadium by strengthening the low-temperature single-step sodium roasting-water leaching process through regulating the crystal grain size and crystallinity of converter vanadium slag. It solves the problems such as when the roasting temperature is higher than 750 - 800 °C, the rotary kiln is prone to sintering and forming a ring, reducing the processing capacity of the kiln, and low production efficiency.

[0005] The present invention is based on the traditional two-step sodium roasting-water leaching vanadium extraction process. The vanadium-containing converter slag is first granulated after mechanical activation, and then the pellet particles are sodium roasted at low temperature and then water-leached, so that the vanadium is efficiently and fully leached into the solution, while the associated macro-elements such as iron, manganese, titanium and other metals remain in the slag. This process promotes the mineral phase transformation of the vanadium carrier phase in the low-temperature single-step sodium roasting process, ensuring efficient vanadium extraction without furnace slagging. The single-step roasting process reduces the waste of energy and additives generated by traditional secondary roasting, improves the working environment, prevents furnace slagging, reduces the consumption of ammonia nitrogen wastewater in the subsequent vanadium precipitation process, ensures the smooth progress of the production process, and ultimately improves production efficiency. It has the characteristics of low energy consumption, less pollution, and high comprehensive recovery rate, meeting the requirements of clean production. The specific steps are as follows:

[0006] (1) mechanically activating converter vanadium slag to obtain activated vanadium slag meeting grain size requirements;

[0007] (2) fully mixing the activated vanadium slag obtained in step (1) with sodium carbonate, sodium chloride and bentonite to obtain a mixture;

[0008] (3) granulating the mixture obtained in step (2) by water spraying to obtain vanadium slag pellets;

[0009] (4) roasting the vanadium slag pellets obtained in step (3) and adjusting the crystallinity of the product phase, and then air-cooling to room temperature to obtain roasted clinker;

[0010] (5) Leaching the roasted clinker obtained in step (4) with water to obtain a leachate and leach residue.

[0011] The treated converter vanadium slag contains V 5-10%, Fe 30-50%, Ti 5-10%, Ca 5-10%, Al 1-10%, and Mn 5-10%.

[0012] In step (1), the vanadium slag is finely ground by mechanical activation to a particle size of less than 18 μm.

[0013] In step (2), the amount of bentonite added is 2% of the mass of the vanadium slag, the amount of sodium carbonate added is 13% of the mass of the vanadium slag, and the mass fraction of sodium chloride is 4% of the mass of the vanadium slag.

[0014] The pelletized particles produced by granulation in step (3) have a particle size of less than 2 mm.

[0015] The calcination temperature used for sodium calcination in step (4) is 750-800°C, the heating rate is 5-10°C / min, and after the calcination completes the phase transformation, the crystallinity of the product phase is controlled at a temperature of 700-720°C, and the insulation time is 1.5-3h.

[0016] In step (5), the leaching temperature for water immersion is 50 - 80°C, the liquid-solid ratio for leaching is 4:1, the stirring speed is 100 - 600 r / min, and the leaching time is 30 - 60 min.

[0017] The beneficial effects of the above technical solution of the invention are as follows:

[0018] In the above solution, more efficient cleaning of vanadium extraction is achieved. The regulation of crystal grain size and crystallinity promotes the phase transformation of the single-step sodium roasting process at low temperature, ensuring efficient vanadium extraction without furnace slagging, and ensuring the smooth progress of the production process. The low-temperature single-step roasting process reduces the waste of energy and additives generated by the secondary roasting process, improves the working environment, reduces the generation of high-sodium ammonia-nitrogen wastewater, and ultimately improves production efficiency. It has the characteristics of low energy consumption, less pollution, and high comprehensive recovery rate, meeting the requirements of clean production. Description of the Drawings

[0019] Figure 1 It is a process flow chart of the method for enhancing vanadium extraction from low-temperature single-step sodium roasting of converter vanadium slag in the present invention. Specific Embodiments

[0020] To make the technical problems, technical solutions, and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the drawings and specific embodiments.

[0021] The present invention provides a method for enhancing vanadium extraction with high efficiency from the regulation of crystal grain size and crystallinity in low-temperature single-step sodium roasting - water immersion process of converter vanadium slag. As Figure 1 shown, it is the process flow chart of this method. This method mainly includes steps such as mechanical activation, granulation, sodium roasting, crystallinity regulation, water immersion, etc., which will be described below through specific embodiments.

[0022] Example 1

[0023] (1) 20 g of converter vanadium slag (containing 6.74% V, 39.28% Fe, 6.73% Ti, 2.67% Ca, 1.73% Al, 5.21% Mn) and a total of 400 g of zirconia balls with different diameters were loaded into a zirconia grinding jar, the grinding lid was locked, and ball milled at a speed of 350 r / min for 20 min to obtain a mechanically activated fine-ground vanadium slag sample with a particle size less than 20 μm.

[0024] (2) Take 20 g of the fine-ground vanadium slag obtained in step (1), 0.4 g of bentonite (accounting for 2% of the mass), 2.6 g of Na2CO3 (accounting for 13% of the mass), and 0.8 g of NaCl (accounting for 4% of the mass) and mix them on a porcelain plate for 5 min. During this process, Na2CO3 and NaCl were first ground for 3 min to ensure that their particle size was less than 0.074 mm.

[0025] (3) Put the mixture obtained in step (2) into a glass dish with a diameter of 15 cm, and spray water while shaking to prepare pellets with a diameter less than 2 mm.

[0026] (4) Take 10 g of the pellets obtained in step (3) and put them into a square crucible. Then the crucible is heated in a muffle furnace from room temperature at a heating rate of 10 °C per minute to 750 °C, kept at this temperature for 30 min, then cooled to 720 °C and kept at this temperature for another 120 min in an air atmosphere. After the heat preservation is completed, take out the crucible and cool it to room temperature in air. After cooling, take out the clinker, grind it with the crucible and pass it through a 80-mesh standard sieve.

[0027] (5) Leach the clinker obtained in step (4) with an aqueous solution. The liquid-solid ratio during the leaching process is 4:1, the leaching temperature is 80 °C, the leaching time is 45 min, and the vanadium leaching rate is 97.65%.

[0028] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for extracting vanadium by low-temperature single-step sodium roasting for regulating the crystal grain size and crystallinity of converter vanadium slag, which is characterized in that: Here are the steps: (1) mechanically activating converter vanadium slag to obtain activated vanadium slag meeting grain size requirements; (2) fully mixing the activated vanadium slag obtained in step (1) with sodium carbonate, sodium chloride and bentonite to obtain a mixture; (3) granulating the mixture obtained in step (2) by water spraying to obtain vanadium slag pellets; (4) roasting the vanadium slag pellets obtained in step (3) and adjusting the crystallinity of the product phase, and then air-cooling to room temperature to obtain roasted clinker; (5) Leaching the roasted clinker obtained in step (4) with water to obtain a leachate and leach residue.

2. The low-temperature single-step sodium roasting vanadium extraction method for regulating the crystal grain size and crystallinity of converter vanadium slag according to the claim, characterized in that: The treated converter vanadium slag contains V 5-10%, Fe 30-50%, Ti 5-10%, Ca 5-10%, Al 1-10%, and Mn 5-10%.

3. The method for extracting vanadium by low-temperature single-step sodium roasting for regulating the crystal grain size and crystallinity of converter vanadium slag according to claim 1, characterized in that: In step (1), the vanadium slag is finely ground by mechanical activation to a particle size of less than 18 μm.

4. The method for extracting vanadium by low-temperature single-step sodium roasting for regulating the crystal grain size and crystallinity of converter vanadium slag according to the claims, characterized in that: In step (2), the amount of bentonite added is 2% of the mass of the vanadium slag, the amount of sodium carbonate added is 13% of the mass of the vanadium slag, and the mass fraction of sodium chloride is 4% of the mass of the vanadium slag. The particle size of the pellets prepared by granulation in step (3) is less than 2 mm.

5. The method for extracting vanadium by low-temperature single-step sodiumization roasting for regulating the crystal grain size and crystallinity of converter vanadium slag according to the claim is characterized in that: The calcination temperature used for sodium calcination in step (4) is 750-800°C, the heating rate is 5-10°C / min, and after the calcination completes the phase transformation, the crystallinity of the product phase is controlled at a temperature of 700-720°C, and the insulation time is 1.5-3h.

6. The method for extracting vanadium by low-temperature single-step sodiumization roasting for regulating the crystal grain size and crystallinity of converter vanadium slag according to the claim, characterized in that: The leaching temperature of the water leaching in step (5) is 50-80° C., the liquid-solid ratio of the leaching is 4:1, the stirring speed is 100-600 r / min, and the leaching time is 30-60 min.

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