Method for leaching vanadium-containing solution through temperature-controlled crystallization, regulation, reinforcement and salt-free roasting of molten vanadium slag

Abstract

The invention discloses a method for leaching a vanadium-containing solution through temperature-control crystallization regulation and strengthening salt-free roasting of molten vanadium slag, and belongs to the technical field of rare metal metallurgy. The method comprises the specific steps that the molten vanadium slag produced by a converter is cooled to the optimal crystallization point temperature and water-cooled to the room temperature; the water-quenched vanadium slag obtained in the step (1) is subjected to salt-free roasting, and vanadium slag clinker is obtained; and levigating the vanadium slag clinker obtained by roasting in the step (2), and leaching with acid to obtain a vanadium-containing solution and leaching slag. Compared with a direct water quenching and slow cooling process, the process has the advantages that the leaching rate of the vanadium-containing solution is increased, the production time and the slow cooling field are saved, high-efficiency vanadium extraction of salt-free roasting is realized, the cooling time is shortened, the roasting temperature is reduced, the use amount of additives is reduced, and the process has the advantages of short production period, high efficiency and low cost; and the clean production requirement is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of rare metal metallurgy, and particularly relates to a method for regulating and strengthening the salt-free roasting and leaching of vanadium-containing solution by controlling the temperature and crystallization of molten vanadium slag. Background Art

[0002] Vanadium is a scarce resource, known as the "monosodium glutamate of modern industry". 88% of the world's annual vanadium production is obtained from converter vanadium slag. The processes for extracting vanadium from vanadium slag mainly include sodium roasting, calcium roasting, and salt-free roasting methods. Compared with sodium roasting and calcium roasting, the salt-free roasting process does not produce toxic gases such as Cl2 and SO2, nor highly carcinogenic chromates, and eliminates the addition of salt additives. It has the advantages of low production cost, high product purity, and simple process, and has great research value and development potential. In actual factory production, molten vanadium slag is transported to a dedicated cooling site by a slag ladle and slowly cooled naturally at room temperature, and the slow cooling time is usually more than 15h. With the expansion of production scale, the space for slow cooling of slag ladles is insufficient. In order to improve production efficiency, the slag ladles are quenched with water on site, resulting in a decrease in the vanadium extraction rate and large fluctuations.

[0003] Generally speaking, the roasting conversion rate and vanadium extraction rate of slowly cooled vanadium slag are better than those of directly water-quenched vanadium slag. However, some vanadium slag that is slowly cooled to different temperatures and then water-quenched also shows high conversion rates and vanadium extraction rates during salt-free roasting and acid leaching. Slow cooling of molten vanadium slag is beneficial for the full migration of vanadium from the molten liquid phase to the vanadium iron spinel phase. At the same time, slow cooling helps the crystallization and growth of vanadium iron spinel. In the crushing and grinding stage, it is easy to dissociate into monomers or expose the surface, and in the subsequent salt-free roasting stage, it can avoid being wrapped by fayalite and silicate glass phases, improving the phase conversion rate of vanadium spinel and the leaching rate of vanadium in the acid leaching stage. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for regulating and strengthening the salt-free roasting and leaching of vanadium-containing solution by controlling the temperature and crystallization of molten vanadium slag, which overcomes the drawbacks of the decline in vanadium extraction rate and large fluctuations based on the direct slow cooling and direct water quenching of current converter vanadium slag. The specific steps are as follows:

[0005] (1) Cool the molten vanadium slag produced by the converter to the optimal crystallization point temperature and then water-cool it to room temperature;

[0006] (2) Subject the water-quenched vanadium slag obtained in step (1) to salt-free roasting to obtain vanadium slag clinker;

[0007] (3) Grind the vanadium slag clinker obtained by roasting in step (2) and then leach it with acid to obtain a vanadium-containing solution and leaching residue.

[0008] Among them, the converter vanadium slag to be treated contains 5-10% V, 5-10% Ti, 5-10% Ca, 1-10% Al, 5-10% Mn, and the balance is Fe.

[0009] The optimal crystallization point of converter vanadium slag in step (1) is 850 - 950 °C.

[0010] In step (2), the roasting temperature is 750 - 900 °C and the roasting time is 60 - 180 min.

[0011] In step (3), the roasted product is ground to a particle size less than 0.18 mm, the acid leaching temperature is 40 - 80 °C, the sulfuric acid concentration is 60 - 180 g / L, the liquid-solid ratio is 5:1, the leaching time is 40 - 180 min, and the stirring speed is 350 r / min.

[0012] The beneficial effects of the above technical solutions of the present invention are as follows:

[0013] In the above solution, compared with the current direct water quenching and slow cooling processes, this process takes into account improving the leaching rate of vanadium-containing solution, saving production time and slow cooling site, realizing efficient vanadium extraction by salt-free roasting, shortening the cooling time and reducing the roasting temperature at the same time, having the advantages of short production cycle, high efficiency and low cost, and meeting the requirements of clean production. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a process flow chart of the method for strengthening salt-free roasting and leaching vanadium-containing solution by controlling temperature crystallization of molten vanadium slag according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] The present invention provides a method for strengthening salt-free roasting and leaching vanadium-containing solution by controlling temperature crystallization of molten vanadium slag. As Figure 1 shown, it is a process flow chart of this method. This method mainly includes steps such as crystal control cooling, water quenching, salt-free roasting, acid leaching, etc., which will be described below through specific embodiments.

[0017] Example 1

[0018] (1) Place 200 g of powdered (<74 μm) vanadium slag (containing 6.07% V, 45.01% Fe, 6.54% Ti) in a crucible and heat it from room temperature to 1400 °C at a heating rate of 5 °C / min and hold for 1 h.

[0019] (2) Cool the molten vanadium slag obtained in step (1) to 900 °C with the furnace and take it out and water cool it to room temperature to obtain water-quenched vanadium slag.

[0020] (3) Weigh 20 g of the water-quenched vanadium slag obtained in step (2), put it into a muffle furnace, heat it from room temperature to 800 °C at a heating rate of 10 °C / min, hold for 120 min, then take it out and air-cool it to room temperature to obtain the calcined clinker.

[0021] (4) Grind the calcined clinker obtained in step (2) to a particle size less than 0.18 mm and then perform acid leaching. The acid leaching temperature is 60 °C, the liquid-solid ratio is 5:1, the leaching time is 120 min, the stirring speed is 350 r / min, and the vanadium leaching rate is 97.65%.

[0022] Example 2

[0023] (1) Place 150 g of powdered (<74 μm) vanadium slag (containing 8.03% V, 44.40% Fe, 4.30% Ti) in a crucible, heat it from room temperature to 1400 °C at a heating rate of 5 °C / min, and hold for 1 h.

[0024] (2) Cool the molten vanadium slag obtained in step (1) in the furnace to 900 °C, take it out, and water-cool it to room temperature to obtain the water-quenched vanadium slag.

[0025] (3) Weigh 20 g of the water-quenched vanadium slag obtained in step (2), mix it thoroughly with 2 g of Na2CO3 and 0.6 g of NaCl in a crucible. Put the mixed powder sample into a muffle furnace, heat it from room temperature to 780 °C at a heating rate of 5 °C / min, hold for 200 min, then take it out and air-cool it to room temperature to obtain the calcined clinker.

[0026] (4) Grind the calcined clinker obtained in step (2) to a particle size less than 0.18 mm and then perform acid leaching. The acid leaching temperature is 80 °C, the liquid-solid ratio is 4:1, the leaching time is 45 min, the stirring speed is 200 r / min, and the vanadium leaching rate is 95.09%.

[0027] Example 3

[0028] Actual production case of a sodium roasting - water leaching vanadium plant in Hebei

[0029] (1) Pour the molten vanadium slag (containing 10.05% V, 42.40% Fe, 4.40% Ti) into a slag ladle and slowly cool it in the air to 900 °C.

[0030] (2) Quench the semi-molten vanadium slag obtained in step (1) which has been slowly cooled to 900 °C with cold water and quickly cool it to room temperature to obtain the water-quenched vanadium slag.

[0031] (3) After crushing the water-quenched vanadium slag obtained in step (2) with a jaw crusher, wet ball mill it to a particle size less than 0.15 mm to obtain the finely ground vanadium slag.

[0032] (4) Filter the finely ground vanadium slag obtained in step (3) and dry it until the mass fraction of moisture is less than 10%. Add 10% by mass of Na2CO3 and 3% by mass of NaCl to the dried vanadium slag and mix well. Load the mixed powder sample into a rotary kiln, roast it at 780 °C for 200 min, and then air-cool it to room temperature to obtain roasted ore.

[0033] (5) Grind the roasted ore obtained in step (4) to a particle size less than 0.074 mm and then leach it with water. The water leaching temperature is 80 °C, the liquid-solid ratio is 3:1, the leaching time is 45 min, and the stirring speed is 200 r / min. The vanadium leaching rate is 85.00%, which is 8-10% higher than the vanadium leaching rate after directly slow-cooling the molten vanadium slag to room temperature and 10-20% higher than the vanadium leaching rate after directly water-quenching the molten vanadium slag to room temperature. The temperature-controlled crystallization regulation technology for molten vanadium slag is also applicable to the sodium roasting process to improve the vanadium leaching rate.

Claims

1. A method for controlling temperature crystallization of molten vanadium slag to regulate and strengthen the leaching of vanadium-containing solution by salt-free roasting, characterized in that The specific steps are as follows: (1) Cool the molten vanadium slag produced by the converter to the optimal crystallization point temperature and then water-cool it to room temperature; (2) Conduct salt-free roasting on the water-quenched vanadium slag obtained in step (1) to obtain vanadium slag clinker; (3) Grind the vanadium slag clinker roasted in step (2) and then leach it with acid to obtain a vanadium-containing solution and leaching residue.

2. The method for controlling temperature crystallization of molten vanadium slag to regulate and strengthen the salt-free roasting and leaching of vanadium-containing solution according to claim 1, characterized in that, The treated converter vanadium slag contains 5-10% V, 5-10% Ti, 5-10% Ca, 1-10% Al, 5-10% Mn, and the balance is Fe.

3. The method for regulating and strengthening the leaching of vanadium-containing solution by salt-free roasting through temperature-controlled crystallization of molten vanadium slag according to claim 1, wherein, In step (1), the optimal crystallization point of the converter vanadium slag is 850-950 °C.

4. The method for regulating and strengthening the leaching of vanadium-containing solution by salt-free roasting through temperature-controlled crystallization of molten vanadium slag according to claim 1, wherein In step (2), the roasting temperature is 750-900 °C and the roasting time is 60-180 min.

5. The method for controlling temperature crystallization of molten vanadium slag to regulate and strengthen the salt-free roasting and leaching of vanadium-containing solution according to claim 1, characterized in that, In step (3), grind the roasted product to a particle size less than 0.18 mm, the acid leaching temperature is 40-80 °C, the sulfuric acid concentration is 60-180 g / L, the liquid-solid ratio is 5:1, the leaching time is 40-180 min, and the stirring speed is 350 r / min.

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