Apparatus and method for sulphuric acid decomposition of a uranium-niobium polymetallic ore

Abstract

This invention provides a sulfuric acid decomposition apparatus and method for uranium-niobium polymetallic ores, relating to the field of hydrometallurgical technology. The apparatus provided by this invention performs sulfuric acid decomposition on uranium-niobium polymetallic ores, realizing the mixing, ripening, and leaching processes of ore powder and concentrated sulfuric acid. Through the integrated decomposition-leaching tank design, the high-temperature acidolysis and leaching processes are carried out within the same equipment, reducing system equipment configuration and avoiding the transfer of high-temperature, high-acid materials between decomposition and extraction equipment. The "dynamic" ripening-"self-heating" enhanced decomposition process strengthens reaction mass transfer and reduces energy consumption. This invention achieves efficient extraction of valuable metals uranium and niobium from complex uranium-niobium polymetallic ores. It does not use fluorine-containing substances, has low reagent costs, and does not generate fluorine-containing wastewater, solving the technical challenges of extracting uranium-niobium polymetallic ores. Furthermore, the apparatus provided by this invention has advantages such as simple equipment configuration, low energy consumption, and high extraction rate of valuable metals.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, specifically to a sulfuric acid decomposition apparatus and method for uranium-niobium polymetallic ores. Background Technology

[0002] As uranium resources are continuously developed, easily mined ores are becoming increasingly scarce. Meanwhile, complex uranium polymetallic ores, with their large reserves, associated strategic metals, and high value, are attracting increasing attention from production enterprises and have become a hot research area for scientific research institutions and universities. Complex uranium polymetallic ores are generally minerals containing uranium, titanium, niobium, and tantalum. Their composition is complex, their chemical stability is high, and they are often found within recalcitrant minerals such as monazite and biotite, making them difficult to process.

[0003] To address the challenges of processing such refractory ores, patent CN111020186A discloses a method for the comprehensive recovery of uranium, niobium, and titanium from niobium-titanium uranium ore. This method involves leaching the ore with sulfuric acid and hydrofluoric acid, adding 10–60 wt% sulfuric acid and 1–8 wt% hydrofluoric acid, and stirring the leaching process at 50–90°C for 1–8 hours. The leaching rates for uranium, niobium, and titanium are 98.4%, 80.3%, and 47.4%, respectively, achieving comprehensive extraction of uranium, niobium, and titanium. However, this method relies on the strong corrosiveness of hydrofluoric acid to increase the extraction rate of valuable metals, resulting in high reagent costs and significant difficulties in treating the fluoride-containing wastewater.

[0004] Zhou Chunyan et al. (Zhou Chunyan, Tan Zhongren, Li Shunan, et al. Study on treatment of uranium pyrochlore-niobium-titanium uranium ore [J]. Nonferrous Metals (Mineral Processing), 1981(05):54.) proposed a sulfuric acid-potassium fluorosilicate co-leaching process for uranium pyrochlore-niobium-titanium uranium ore. The amounts of sulfuric acid, potassium fluorosilicate, and manganese dioxide were 16%, 5%, and 2% of the ore mass, respectively. The grinding particle size was -0.2 mm. The leaching was carried out at 80℃ with stirring for 3 hours, and the uranium leaching rate reached 93%, while the niobium leaching rate was over 63%. This process achieved simultaneous leaching of uranium and niobium, but it still had disadvantages such as high reagent costs and complex treatment of fluoride-containing wastewater. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a sulfuric acid decomposition apparatus and method for uranium-niobium polymetallic ores. By using the sulfuric acid decomposition apparatus provided by this invention to leach uranium-niobium polymetallic ores after aging with concentrated sulfuric acid, the valuable metals uranium and niobium in complex polymetallic ores containing uranium and niobium can be efficiently extracted. This invention does not use fluorine-containing substances, has low reagent costs, and does not generate fluorine-containing wastewater.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a sulfuric acid decomposition device for uranium-niobium polymetallic ores, comprising:

[0008] The mixer 3 is equipped with a stirring device, a mineral powder inlet, a sulfuric acid feed pipe, and a discharge outlet; a valve is installed on the sulfuric acid feed pipe.

[0009] The decomposition-leaching integrated tank 4 is connected to the discharge port of the mixer 3. The decomposition-leaching integrated tank 4 is also equipped with a water inlet pipe, a compressed air inlet pipe, a steam inlet pipe, a discharge port, and a compressed air-steam mixing device 4-1. Valves are installed on the water inlet pipe, the compressed air inlet pipe, and the steam inlet pipe.

[0010] Preferably, the sulfuric acid decomposition apparatus further includes:

[0011] The feeder 2 has its discharge port connected to the mineral powder inlet of the mixer 3, and the feeder 2 is also provided with a mineral powder inlet;

[0012] The discharge port of the ore bin 1 is connected to the ore powder inlet of the feeder 2.

[0013] Preferably, the sulfuric acid decomposition device further includes a discharge pump 5 whose inlet is connected to the discharge port of the integrated decomposition-leaching tank 4.

[0014] This invention provides a method for sulfuric acid decomposition of uranium-niobium polymetallic ores, using the sulfuric acid decomposition apparatus described above, and includes the following steps:

[0015] Uranium-niobium polymetallic ore powder is mixed with concentrated sulfuric acid in mixer 3 to obtain a mixture;

[0016] Under the first compressed air stirring condition, the mixture is conveyed to the decomposition-leaching integrated tank 4, water is added to dilute concentrated sulfuric acid, and the ore is decomposed under the heat of dilution and the heat of reaction. Then, under the second compressed air stirring condition, water or process water is added for leaching to obtain an acid leaching solution of uranium-niobium polymetallic ore. The concentration of sulfuric acid in the process water is 0.3-1.5 mol / L, the concentration of uranium is 10-40 mg / L, and the concentration of niobium is 25-100 mg / L.

[0017] Preferably, the concentrated sulfuric acid has a mass fraction of 90-98%;

[0018] The mass ratio of the uranium-niobium polymetallic ore powder to concentrated sulfuric acid is 1:0.4-2.

[0019] Preferably, the compressed air pressure for the first compressed air agitation is 300-600 kPa;

[0020] The mass ratio of the uranium-niobium polymetallic ore powder to the dilution water is 1:0.2-1.5;

[0021] The ore decomposition temperature is 100–200℃, and the time is 30–120 min.

[0022] Preferably, the solid-liquid ratio of the uranium-niobium polymetallic ore powder to the process water is 1 kg: 2-5 L.

[0023] Preferably, the compressed air pressure for the second compressed air agitation is 400–800 kPa;

[0024] The leaching time is 0.5 to 2 hours.

[0025] Preferably, the sulfuric acid decomposition method further includes: separating uranium and niobium in the acid hydrolysis leaching solution of the uranium-niobium polymetallic ore to obtain uranium product, niobium product and metal separation solution respectively; the metal separation solution is transported to the decomposition-leaching integrated tank 4 to replace water for diluting concentrated sulfuric acid and as process water for the leaching step.

[0026] Preferably, the uranium-niobium separation includes thermal precipitation of niobium and uranium extraction; the thermal precipitation of niobium and uranium extraction have no temporal order.

[0027] The temperature for the thermal precipitation of niobium is 150–250°C, and the time is 1–2 hours.

[0028] The uranium extraction employs an extractant system comprising a primary extractant, a secondary extractant, and a diluent. The primary extractant comprises diisooctyl phosphate and / or tri-n-octylamine; the secondary extractant comprises one or more of tributyl phosphate, trialkylphosphine oxide, and isodecanol; the diluent comprises sulfonated kerosene; the volume fraction of the primary extractant in the extractant system is 3–5%, and the volume fraction of the secondary extractant is 5–15%; the uranium extraction time is 3–5 minutes.

[0029] During the reuse process of the metal-separated solution, the mass ratio of uranium-niobium polymetallic ore powder to the metal-separated solution is 1:0.2 to 1.5, and the time for the metal-separated solution to be transported to the decomposition-leaching integrated tank 4 is 10 to 30 minutes.

[0030] The sulfuric acid decomposition device for uranium-niobium polymetallic ores provided by this invention performs sulfuric acid decomposition on uranium-niobium polymetallic ores, realizing the mixing, ripening, and leaching process of mineral powder and concentrated sulfuric acid. Through the integrated design of the process and decomposition-leaching tank, the high-temperature acidolysis and leaching processes are carried out in the same equipment, reducing the system equipment configuration and avoiding the transfer of high-temperature, high-acid materials between decomposition and extraction equipment. The "dynamic" ripening-"self-heating" enhanced decomposition process strengthens reaction mass transfer and reduces energy consumption, achieving a 60% reduction in energy consumption compared to current rotary kiln roasting equipment. This invention achieves efficient extraction of valuable metals uranium and niobium from complex uranium-niobium polymetallic ores. It does not use fluorine-containing substances, has low reagent costs, and does not generate fluorine-containing wastewater, solving the technical challenges of extracting uranium-niobium polymetallic ores. Moreover, the device provided by this invention has the advantages of simple equipment configuration, low energy consumption, and high extraction rate of valuable metals. As shown in the test results of the examples, the sulfuric acid decomposition device provided by the present invention can be used to extract uranium and niobium from uranium-niobium polymetallic ores. The extraction rate of uranium is above 95%, and the extraction rate of niobium is above 85%. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a sulfuric acid decomposition device for uranium-niobium polymetallic ores. In the diagram, 1 is the ore bin, 2 is the feeder, 3 is the mixer, 4 is the decomposition-leaching integrated tank, 4-1 is the compressed air-steam mixing device, and 5 is the discharge pump. Detailed Implementation

[0032] This invention provides a sulfuric acid decomposition device for uranium-niobium polymetallic ores, comprising:

[0033] The mixer 3 is equipped with a stirring device, and is also equipped with a mineral powder inlet, a sulfuric acid feed pipe and a discharge outlet.

[0034] The decomposition-leaching integrated tank 4 is connected to the discharge port of the mixer 3. The decomposition-leaching integrated tank 4 is also equipped with a water inlet pipe, a compressed air inlet pipe, a steam inlet pipe and a discharge port; valves are installed on both the compressed air inlet pipe and the steam inlet pipe.

[0035] Figure 1 This is a schematic diagram of a sulfuric acid decomposition device for uranium-niobium polymetallic ores. The following section combines... Figure 1 A detailed description is provided of the sulfuric acid decomposition apparatus for uranium-niobium polymetallic ores.

[0036] The sulfuric acid decomposition device for uranium-niobium polymetallic ores provided by the present invention preferably includes a ore bin 1, wherein the ore bin 1 is provided with a discharge port.

[0037] The sulfuric acid decomposition device for uranium-niobium polymetallic ore provided by the present invention preferably includes a feeder 2, which is provided with an inlet and an outlet. The inlet is connected to the outlet of the ore bin 1. The feeder 2 is used to measure the amount of sulfuric acid added to the mixer 3.

[0038] The sulfuric acid decomposition device for uranium-niobium polymetallic ores provided by the present invention includes a mixer 3, which is equipped with a stirring device. The present invention does not have any special limitation on the stirring device, and any stirring device well known to those skilled in the art can be used, such as a spiral ribbon or a pair of double spirals. The mixer 3 is also provided with a mineral powder inlet, a sulfuric acid feed pipe and a discharge port. The mineral powder inlet is connected to the discharge port of the feeder 2. A valve is provided on the sulfuric acid feed pipe to control the amount of concentrated sulfuric acid added to the mixer 3.

[0039] The sulfuric acid decomposition apparatus for uranium-niobium polymetallic ores provided by this invention includes an integrated decomposition-leaching tank 4. The integrated decomposition-leaching tank 4 is equipped with a feed inlet, a water inlet pipe, a compressed air inlet pipe, a steam inlet pipe, a discharge outlet, and a compressed air-steam mixing device 4-1. The feed inlet is connected to the discharge outlet of the mixer 3. Valves are installed on the water inlet pipe, the compressed air inlet pipe, and the steam inlet pipe. In this invention, the air inlet of the compressed air-steam mixing device 4-1 is connected to both the compressed air inlet pipe and the steam inlet pipe. In this invention, the decomposition-leaching integrated tank 4 preferably includes a straight cylindrical section and a conical section with a cone angle. The diameter of the straight cylindrical section is preferably 300-1000 mm, more preferably 500-800 mm, and the height of the straight cylindrical section is preferably 1200-4000 mm, more preferably 2000-3000 mm. The angle of the conical section is preferably 45-60°, more preferably 50-55°. In this invention, the compressed air-steam mixing device 4-1 is preferably disposed at the bottom of the decomposition-leaching integrated tank 4 for mixing compressed air and steam. The compressed air-steam mixing device 4-1 preferably has several air outlets. The compressed air-steam mixing device 4-1 preferably comprises a stainless steel pipe, more preferably a 316L stainless steel pipe. The inner diameter of the stainless steel pipe is preferably 75–150 mm, and the length of the stainless steel pipe is preferably 300–600 mm. Both ends of the stainless steel pipe are preferably sealed by welding with steel plates. The dimensions of the stainless steel pipe are preferably such that both ends of the pipe are tightly welded with steel plates. The air outlets are preferably evenly distributed on the pipe wall of the stainless steel pipe. The shape of the air outlets preferably includes an elliptical shape. The size of the air outlets is preferably 20 × 10 mm. The opening ratio of the air outlets is preferably 15–30%, more preferably 20–25%.

[0040] The sulfuric acid decomposition device for uranium-niobium polymetallic ores provided by the present invention preferably includes a discharge pump 5, which is provided with an inlet and an outlet. The inlet is connected to the discharge port of the decomposition-leaching integrated tank 4, and a valve is preferably provided on the connecting pipe.

[0041] This invention also provides a method for sulfuric acid decomposition of uranium-niobium polymetallic ores, which utilizes the sulfuric acid decomposition apparatus described in the above technical solution and includes the following steps:

[0042] Uranium-niobium polymetallic ore powder is mixed with concentrated sulfuric acid in mixer 3 to obtain a mixture;

[0043] Under the first compressed air stirring condition, the mixture is conveyed to the decomposition-leaching integrated tank 4, water is added to dilute concentrated sulfuric acid, and the ore is decomposed under the heat of dilution and the heat of reaction. Then, under the second compressed air stirring condition, water or process water is added for leaching to obtain an acid leaching solution of uranium-niobium polymetallic ore. The concentration of sulfuric acid in the process water is 0.3-1.5 mol / L, the concentration of uranium is 10-40 mg / L, and the concentration of niobium is 25-100 mg / L.

[0044] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field.

[0045] In this invention, uranium-niobium polymetallic ore powder is mixed with concentrated sulfuric acid in a mixer 3 to obtain a mixture.

[0046] This invention does not specifically limit the uranium-niobium polymetallic ore powder used; any uranium-niobium polymetallic ore powder well-known to those skilled in the art can be used. Specifically, it can be a complex polymetallic ore powder containing niobium-titanium uranium minerals, or a ore powder containing niobium-iron-niobium-manganese ore, pyrochlore, and calcite, or a pyrochlore-niobium-titanium uranium type polymetallic ore. In this invention, the uranium grade in the uranium-niobium polymetallic ore powder is preferably 0.05–0.825%, more preferably 0.085–0.425%; the niobium grade in the uranium-niobium polymetallic ore powder is preferably 0.3–20%, more preferably 0.4–15%. In a specific embodiment of the present invention, the uranium grade in the complex polymetallic ore powder containing niobium-titanium uranium minerals is 0.425%, and the niobium grade is 0.56%; the uranium grade in the ore powder containing niobium-iron-niobium-manganese ore, pyrochlore, and calcite is 0.12%, and the niobium grade is 15.85%; the uranium grade in the pyrochlore-niobium-titanium uranium ore type polymetallic ore is 0.085%, and the niobium grade is 1.86%. In the present invention, the particle size of the uranium-niobium polymetallic ore powder is preferably 0.02-0.2 mm, more preferably 0.03-0.1 mm.

[0047] In this invention, the mass fraction of the concentrated sulfuric acid is preferably 90-98%, more preferably 91-97%, and even more preferably 92-95%, specifically preferably 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, or 98%.

[0048] In this invention, the mass ratio of the uranium-niobium polymetallic ore powder to concentrated sulfuric acid is preferably 1:0.4 to 2, more preferably 1:0.4 to 1.5, even more preferably 1:0.4 to 1.2, and specifically preferably 1:0.4, 1:0.8 or 1:1.2.

[0049] The present invention does not have any special limitations on the mixing, as long as the raw materials are mixed evenly, such as by stirring.

[0050] After obtaining the mixture, the present invention conveys the mixture to the decomposition-leaching integrated tank 4 under the first compressed air stirring condition, adds water to dilute concentrated sulfuric acid, decomposes the ore under the heat of dilution and the heat of reaction, and then adds water or process water under the second compressed air stirring condition to leach, thereby obtaining an acid leaching solution of uranium-niobium polymetallic ore; the concentration of sulfuric acid in the process water is 0.3-1.5 mol / L, the concentration of uranium is 10-40 mg / L, and the concentration of niobium is 25-100 mg / L.

[0051] In this invention, the pressure of the compressed air used for the first compressed air agitation is preferably 300-600 kPa, more preferably 400-500 kPa.

[0052] In this invention, the distance between the material loading height (total height of mineral powder, concentrated sulfuric acid and process water) inside the integrated decomposition-leaching tank 4 and the top of the integrated decomposition-leaching tank 4 is preferably 500-800 mm, more preferably 600-800 mm, and even more preferably 700-800 mm.

[0053] In this invention, the mass ratio of the uranium-niobium polymetallic ore powder to the dilution water is preferably 1:0.2 to 1.5, more preferably 1:0.2 to 1, even more preferably 1:0.2 to 0.5, and specifically preferably 1:0.2, 1:0.25 or 1:0.3.

[0054] In this invention, the temperature for ore decomposition is preferably 100-200℃, more preferably 120-200℃, and even more preferably 160-180℃; the time for ore decomposition is preferably 30-120 min, more preferably 50-120 min, and even more preferably 90-120 min.

[0055] In this invention, the dilution water is preferably added at a time of 10-30 minutes, more preferably 10-20 minutes. The dilution water is added slowly, and the heat of reaction and the heat of dilution of concentrated sulfuric acid in this process can maintain the slurry temperature at 100-200°C. When the material temperature is lower than the preset decomposition temperature, the compressed air flow rate is reduced and steam is turned on to maintain the temperature required for ore decomposition. The temperature of the steam is preferably 180-250°C, more preferably 180-220°C.

[0056] In this invention, the compressed air pressure for the second compressed air agitation is preferably 400-800 kPa, more preferably 450-600 kPa; the compressed air pressure for the second compressed air agitation is preferably greater than the compressed air pressure for the first compressed air agitation.

[0057] In this invention, the concentration of sulfuric acid in the process water is preferably 0.3–1.5 mol / L, specifically preferably 0.4 mol / L, 0.6 mol / L, or 1.2 mol / L; the concentration of uranium is preferably 10–40 mg / L, specifically preferably 12 mol / L, 15 mol / L, or 40 mg / L; and the concentration of niobium is preferably 25–100 mg / L, specifically preferably 25 mg / L, 85 mg / L, or 98 mg / L.

[0058] In this invention, the solid-liquid ratio of the uranium-niobium polymetallic ore powder to the process water is preferably 1 kg: 2-5 L, more preferably 1 kg: 2-4 L, and even more preferably 1 kg: 2-3 L.

[0059] In this invention, the leaching temperature is preferably room temperature, and the leaching time is preferably 0.5 to 2 hours, more preferably 1 to 2 hours, and even more preferably 1.5 to 2 hours.

[0060] After leaching, the present invention preferably further includes pumping the obtained leaching system out via discharge pump 5, and then performing solid-liquid separation, wherein the obtained liquid component is an acid hydrolysis leaching solution of uranium-niobium polymetallic ore. The present invention does not have any particular limitation on the solid-liquid separation; any solid-liquid separation method well known to those skilled in the art can be used, such as pressure filtration, vacuum filtration, or centrifugal separation.

[0061] The sulfuric acid decomposition method provided by the present invention preferably further includes: separating uranium and niobium in the acid hydrolysis leaching solution of the uranium-niobium polymetallic ore to obtain uranium product, niobium product and metal separation solution respectively; the metal separation solution is transported to the decomposition-leaching integrated tank 4 to replace water for diluting concentrated sulfuric acid, and the remaining metal separation solution is used as process water for the leaching step.

[0062] In this invention, the uranium-niobium separation preferably includes thermal precipitation for niobium extraction and uranium extraction; the thermal precipitation for niobium extraction and uranium extraction have no temporal order. Taking thermal precipitation for niobium extraction followed by uranium extraction as an example, the uranium-niobium separation specifically preferably includes: thermal precipitation followed by solid-liquid separation of the acid hydrolysis leaching solution of the uranium-niobium polymetallic ore to obtain niobium precipitate and niobium-removed leaching solution respectively; mixing the niobium-removed leaching solution with an extractant system and performing uranium extraction to obtain a uranium-containing extractant phase (organic phase) and a metal-separated solution (aqueous phase) respectively; concentrating the uranium-containing extractant phase to obtain uranium product and a recovered extractant system, wherein the recovered extractant system is reused.

[0063] In this invention, the temperature for the thermal precipitation of niobium is preferably 150-250°C, more preferably 160-220°C, and even more preferably 180-200°C; the time for the thermal precipitation of niobium is preferably 1-2 hours, more preferably 1.5-2 hours.

[0064] The present invention does not have any particular limitation on the solid-liquid separation, and any solid-liquid separation method known to those skilled in the art can be used, such as pressure filtration, vacuum filtration or centrifugal separation.

[0065] In this invention, the uranium extraction using an extractant system preferably includes a main extractant, a secondary extractant, and a diluent; the main extractant preferably includes diisooctyl phosphate (P204) and / or tri-n-octylamine (N235); the secondary extractant preferably includes one or more of tributyl phosphate (TBP), trialkylphosphine oxide (TRPO), and isodecanol; and the diluent preferably includes sulfonated kerosene. In this invention, the volume fraction of the main extractant in the extractant system is preferably 3-5%, more preferably 3.5-4.5%, and even more preferably 4%; the volume fraction of the secondary extractant in the extractant system is preferably 5-15%, more preferably 8-12%, and even more preferably 10%. In this invention, the ratio of the uranium-niobium polymetallic leaching solution to the extractant system is preferably 1-5:1-5, more preferably 1-3:1-3.

[0066] In this invention, the uranium extraction temperature is preferably room temperature, and the uranium extraction time is preferably 3 to 5 minutes, more preferably 3 to 4 minutes.

[0067] In this invention, the amount and time of addition of the metal-separated solution during the reuse process are the same as those of the dilution water, and will not be repeated here.

[0068] To further illustrate the present invention, the apparatus and method for sulfuric acid decomposition of uranium-niobium polymetallic ores are described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0069] In the following embodiments, the diameter of the straight section of the integrated decomposition-leaching tank 4 of the sulfuric acid decomposition device for uranium-niobium polymetallic ore is 500 mm, the height is 2000 mm, the cone angle of the conical section is 45-60°, and the compressed air-steam mixing device 4-1 is a Φ100*500 mm 316L stainless steel pipe. The two ends of the steel pipe are welded tightly with steel plates, and 20*10 mm elliptical air outlets are evenly distributed on the pipe wall, with an opening rate of 25%.

[0070] Example 1

[0071] Complex polymetallic mineral powder containing niobium, titanium, and uranium (particle size 0–0.074 mm): uranium grade 0.425%, niobium grade 0.56%.

[0072] (1) The mineral powder is fed into the mixer 3 via the feeder 2. The mineral powder and 90wt% concentrated sulfuric acid are mixed in the mixer 3 at a mass ratio of 1:0.8. The resulting mixture is then transported to the decomposition-leaching integrated tank 4. At the same time, compressed air is turned on to agitate the mixture. The compressed air pressure is 500kPa. The loading height is kept 800mm from the top of the decomposition-leaching integrated tank 4. After all the mixture has been added, a metal separation solution (prepared according to step (4) of this embodiment) with a mass of 0.3 times that of the mineral powder is added. The metal separation solution is added in 10min. The heat of reaction and the heat of dilution of concentrated sulfuric acid can make the slurry temperature reach 180℃. The material temperature can be maintained above 160℃ for 120min.

[0073] (2) After the decomposition reaction is completed, the compressed air flow rate is increased to 580 kPa, and process water is added at a liquid-to-solid ratio of 2:1 (L / kg) with the ore powder. The reaction is carried out for 2 hours under the stirring of compressed air to leach valuable metals. After leaching, the leaching is pumped out by discharge pump 5 for solid-liquid separation. The resulting liquid component is acid leaching solution of uranium-niobium polymetallic ore. The concentration of sulfuric acid in the process water is 0.4 mol / L, the concentration of uranium is 15 mg / L, and the concentration of niobium is 85 mg / L.

[0074] (3) The acid leaching solution of the uranium-niobium polymetallic ore was subjected to thermal precipitation to extract niobium at 180°C for 1.5 h, and the solid and liquid were separated to obtain niobium precipitate and niobium-free leaching solution, respectively.

[0075] (4) An extractant system is added to the niobium-removing leaching solution, and uranium extraction is performed at room temperature for 5 minutes to obtain a uranium-containing extractant phase and a metal-separated solution (aqueous phase). The uranium-containing extractant phase is concentrated to obtain uranium products and a recovered extractant system, which is reused. The metal-separated solution is used to dilute concentrated sulfuric acid in step (1), and the remaining metal-separated solution is reused as process water in the leaching step (2). The ratio of uranium-containing leaching solution to extractant system is preferably 1:2. The extractant system, by volume percentage, consists of 5% P2O4, 3% N235, 15% TBP, and the remainder is sulfonated kerosene.

[0076] The uranium extraction rate from the ore powder was 96.8%, and the niobium extraction rate was 88.5%.

[0077] Example 2

[0078] The mineral contains columbite-niobium-manganese ore, pyrochlore and calcite powder (particle size 0-0.1 mm): uranium grade 0.12%, niobium grade 15.85%.

[0079] (1) The mineral powder is fed into the mixer 3 via the feeder 2. The mineral powder and 95wt% concentrated sulfuric acid are mixed in the mixer 3 at a mass ratio of 1:1.2. The resulting mixture is then transported to the decomposition-leaching integrated tank 4. At the same time, compressed air is turned on to agitate the mixture. The compressed air pressure is 480kPa. The loading height is kept 600mm from the top of the decomposition-leaching integrated tank 4. After all the mixture has been added, 0.25 times the mass of the mineral powder is added to the metal separation solution. The metal separation solution (prepared according to step (4) of this embodiment) is added at a time of 15min. The heat of reaction and the heat of dilution of concentrated sulfuric acid can make the slurry temperature reach 200℃. The compressed air flow rate is reduced and steam is turned on. The steam temperature is 220℃. The temperature of the decomposition reaction is kept at 195℃. The total decomposition time is 90min.

[0080] (2) After the decomposition reaction is completed, the compressed air flow rate is increased to 550 kPa, and process water is added at a liquid-to-solid ratio of 3:1 (L / kg) with the ore powder. The reaction is carried out for 0.5 h under the stirring of compressed air to leach valuable metals. After leaching, the leaching is pumped out by discharge pump 5 for solid-liquid separation. The resulting liquid component is acid leaching solution of uranium-niobium polymetallic ore. The concentration of sulfuric acid in the process water is 1.2 mol / L, the concentration of uranium is 40 mg / L, and the concentration of niobium is 98 mg / L.

[0081] (3) The acid leaching solution of the uranium-niobium polymetallic ore was subjected to thermal precipitation to extract niobium at 200°C for 1 hour, and the solid and liquid were separated to obtain niobium precipitate and niobium-free leaching solution, respectively.

[0082] (4) An extractant system is added to the niobium-removing leaching solution, and uranium extraction is performed at room temperature for 3 minutes to obtain a uranium-containing extractant phase and a metal-separated solution (aqueous phase). The uranium-containing extractant phase is concentrated to obtain uranium products and a recovered extractant system, which is reused. The metal-separated solution is used to dilute concentrated sulfuric acid in step (1), and the remaining metal-separated solution is reused as process water in the leaching step (2). The ratio of uranium-containing leaching solution to extractant system is preferably 1.5:1. The extractant system consists of 5% P2O4, 10% TBP, and 5% TRPO by volume percentage, with the remainder being sulfonated kerosene.

[0083] The uranium extraction rate from the ore powder was 95%, and the niobium extraction rate was 92%.

[0084] Example 3

[0085] Pyrochlore-niobium-titanium uranium type polymetallic ore powder (particle size 0-0.15mm): uranium grade 0.085%, niobium grade 1.86%.

[0086] (1) The mineral powder is fed into the mixer 3 via the feeder 2. The concentrated sulfuric acid is added to the mixer 3 according to the mass ratio of mineral powder to 92wt% concentrated sulfuric acid of 1:0.4. The resulting mixture is then transported to the decomposition-leaching integrated tank 4. At the same time, compressed air is turned on to agitate the mixture. The compressed air pressure is 400kPa. The loading height is kept 500mm away from the top of the decomposition-leaching integrated tank 4. After all the mixture has been added, 0.2 times the mass of the mineral powder is added to the metal separation solution. The metal separation solution (prepared according to step (4) of this embodiment) is added at a time of 10min. The heat of reaction and the heat of dilution of concentrated sulfuric acid can make the slurry temperature reach 100℃. The compressed air flow rate is reduced and steam is turned on. The steam temperature is 180℃. The temperature of the decomposition reaction is kept at 160℃. The total decomposition time is 120min.

[0087] (2) After the decomposition reaction is completed, the compressed air flow rate is increased to 450 kPa, and process water is added at a liquid-to-solid ratio of 2:1 (L / kg) with the ore powder. The reaction is carried out for 2 hours under the stirring of compressed air to leach valuable metals. After leaching, the leaching is pumped out by discharge pump 5 for solid-liquid separation. The resulting liquid component is acid leaching solution of uranium-niobium polymetallic ore. The concentration of sulfuric acid in the process water is 0.6 mol / L, the concentration of uranium is 12 mg / L, and the concentration of niobium is 25 mg / L.

[0088] (3) The acid leaching solution of the uranium-niobium polymetallic ore was subjected to thermal precipitation at 190°C for 2 hours to extract niobium. The solid and liquid were separated to obtain niobium precipitate and niobium-free leaching solution, respectively.

[0089] (4) An extractant system is added to the niobium-removing leaching solution, and uranium extraction is performed at room temperature for 5 min to obtain a uranium-containing extractant phase and a metal-separated solution (aqueous phase). The uranium-containing extractant phase is concentrated to obtain uranium products and a recovered extractant system, which is reused. The metal-separated solution is used to dilute concentrated sulfuric acid in step (1), and the remaining metal-separated solution is reused as process water in the leaching step (2). The ratio of uranium-containing leaching solution to extractant system is preferably 2:1. The extractant system consists of 5% N235, 5% TBP, and 5% isodecanol by volume percentage, with the remainder being sulfonated kerosene.

[0090] The uranium extraction rate from the ore powder was 95%, and the niobium extraction rate was 85%.

[0091] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on the present invention without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for sulfuric acid decomposition of uranium-niobium polymetallic ore, characterized in that, The sulfuric acid decomposition is carried out using a sulfuric acid decomposition device, which includes: The mixer (3) is equipped with a stirring device and a mineral powder inlet, a sulfuric acid feed pipe and an outlet; the sulfuric acid feed pipe is equipped with a valve. The decomposition-leaching integrated tank (4) is connected to the discharge port of the mixer (3) through the feed inlet. The decomposition-leaching integrated tank (4) is also equipped with a water inlet pipe, a compressed air inlet pipe, a steam inlet pipe, a discharge port, and a compressed air-steam mixing device (4-1). Valves are provided on the water inlet pipe, the compressed air inlet pipe, and the steam inlet pipe. The sulfuric acid decomposition method includes the following steps: Uranium-niobium polymetallic ore powder is mixed with concentrated sulfuric acid in a mixer (3) to obtain a mixture; the mass fraction of the concentrated sulfuric acid is 90~98%. The mixture is transported to the decomposition-leaching integrated tank (4) under the first compressed air stirring condition, and concentrated sulfuric acid is diluted with water. The ore is decomposed under the heat of dilution and the heat of reaction. Then, process water is added under the second compressed air stirring condition for leaching to obtain uranium-niobium polymetallic ore acid leaching solution. The temperature of the ore decomposition is 100~200℃. The concentration of sulfuric acid in the process water is 0.3~1.5mol / L, the concentration of uranium is 10~40mg / L, and the concentration of niobium is 25~100mg / L.

2. The sulfuric acid decomposition method according to claim 1, characterized in that, The mass ratio of the uranium-niobium polymetallic ore powder to concentrated sulfuric acid is 1:0.4~2.

3. The sulfuric acid decomposition method according to claim 1 or 2, characterized in that, The pressure of the compressed air used for the first compressed air agitation is 300~600kPa; The mass ratio of the uranium-niobium polymetallic ore powder to the dilution water is 1:0.2~1.5; The ore decomposition temperature is 100~200℃, and the time is 30~120min.

4. The sulfuric acid decomposition method according to claim 3, characterized in that, The solid-liquid ratio of the uranium-niobium polymetallic ore powder to the process water is 1 kg: 2~5 L.

5. The sulfuric acid decomposition method according to claim 1 or 4, characterized in that, The compressed air pressure for the second compressed air agitator is 400~800 kPa; The leaching time is 0.5 to 2 hours.

6. The sulfuric acid decomposition method according to claim 1, characterized in that, The sulfuric acid decomposition method further includes: separating uranium and niobium in the acid hydrolysis leaching solution of the uranium-niobium polymetallic ore to obtain uranium product, niobium product and metal separation solution respectively; the metal separation solution is transported to the decomposition-leaching integrated tank (4) to replace water for diluting concentrated sulfuric acid and as process water for the leaching step.

7. The sulfuric acid decomposition method according to claim 6, characterized in that, The uranium-niobium separation includes thermal precipitation of niobium and uranium extraction; the thermal precipitation of niobium and uranium extraction have no temporal order. The temperature for the thermal precipitation of niobium is 150~250℃, and the time is 1~2h; The uranium extraction process employs an extractant system comprising a primary extractant, a secondary extractant, and a diluent. The primary extractant comprises diisooctyl phosphate and / or tri-n-octylamine; the secondary extractant comprises one or more of tributyl phosphate, trialkylphosphine oxide, and isodecanol; and the diluent comprises sulfonated kerosene. The volume fraction of the primary extractant in the extractant system is 3-5%, and the volume fraction of the secondary extractant is 5-15%. The uranium extraction time is 3-5 minutes. During the reuse process of the metal-separated solution, the mass ratio of uranium-niobium polymetallic ore powder to the metal-separated solution is 1:0.2~1.5, and the time for the metal-separated solution to be transported to the decomposition-leaching integrated tank (4) is 10~30 min.

8. The sulfuric acid decomposition method according to claim 1, 2 or 4, characterized in that, The sulfuric acid decomposition apparatus also includes: The feeder (2) whose discharge port is connected to the mineral powder inlet of the mixer (3) is also provided with a mineral powder inlet; The discharge port is connected to the ore powder inlet of the feeder (2) in the ore bin (1).

9. The sulfuric acid decomposition method according to claim 1, 2, 4, 6 or 7, characterized in that, The sulfuric acid decomposition device also includes a discharge pump (5) whose inlet is connected to the discharge port of the decomposition-leaching integrated tank (4).

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