System for preparing crude rare earth by high-pressure nitric acid multi-stage leaching and decomposition of zijing rare earth-containing phosphate ore

Abstract

The utility model discloses a system of high pressure nitric acid multistage leaching decomposition zengjin phosphorite containing rare earth and preparation of crude rare earth, the utility model provides a closed high pressure environment with high pressure reactor, through the leaching reaction of nitric acid to phosphorite, and combines multistage leaching process purification and extracts rare earth element, through the leaching effect of multistage nitric acid can gradually dissolve and separate the element in the mine of zengjin phosphorite, and then removes the impurity through the acidolysis, freezing crystallization, the step such as depth decalcification, then realizes secondary leaching through the acoustic cavitation effect of ultrasonic device, improves the leaching rate of rare earth element in filter cake, and gets crude rare earth enrichment, the utility model improves the rare earth leaching efficiency of zengjin phosphorite to 99%, and utilizes nitric acid phosphate fertilizer device byproduct fertilizer simultaneously.

Description

Technical Field

[0001] This utility model relates to the field of rare earth recycling technology, and in particular to a system for producing crude rare earth from rare earth-containing phosphate rock by high-pressure nitric acid multi-stage leaching and decomposition. Background Technology

[0002] Rare earth elements are strategic resources supporting modern technology. Due to their excellent photoelectric and electromagnetic properties, they can be combined with other materials to form a wide variety of new materials with different properties. Their most significant function is to greatly improve the quality and performance of other products. For example, they can significantly improve the tactical performance of steel, aluminum alloys, magnesium alloys, and titanium alloys used in the manufacture of tanks, aircraft, and missiles. Moreover, rare earth elements also serve as a lubricant for many high-tech industries such as electronics, lasers, nuclear industry, and superconductivity. Their irreplaceability is reflected in their ability to empower the underlying technologies of high-end manufacturing, clean energy, national defense, and information technology, as well as their geopolitical weight in the global supply chain game. Currently, there are two main methods for recycling and producing rare earth elements: acid leaching and alkali fusion.

[0003] The existing acid leaching equipment for extracting rare earths from rare earth-containing phosphate rock has the following drawbacks: the traditional single-stage nitric acid leaching process is not efficient at leaching rare earth elements encapsulated in the phosphate rock lattice, with a leaching rate generally below 65%, resulting in a large amount of rare earth residue remaining in the acid leaching residue. The decalcification process needs to be repeated 3-4 times to reduce the calcium ion concentration to below 0.5 g / L, which prolongs the process. Based on these shortcomings, how to provide a system for the multi-stage leaching of high-pressure nitric acid to decompose rare earth-containing phosphate rock in Zhijin to produce crude rare earths, with multi-stage nitric acid synergistic leaching, precise pH control, deep decalcification and co-production of gypsum, and waste liquid recycling, has become an urgent technical problem to be solved. Utility Model Content

[0004] In view of the shortcomings of the above-mentioned technologies, such as the low leaching rate and poor effect of rare earth elements in Zhijin phosphate rock, this utility model provides a system for producing crude rare earth by high-pressure nitric acid multi-stage leaching decomposition of rare earth-containing phosphate rock in Zhijin.

[0005] To achieve the above objectives, this utility model provides a system for high-pressure nitric acid multi-stage leaching and decomposition of rare earth phosphate rock in Zhijin, used to extract coarse rare earth elements from Zhijin phosphate rock. The system includes a crusher, a calcining furnace, a high-pressure reactor, an acid hydrolysis tank, a first centrifugal filter, a frozen crystallization tank, a second centrifugal filter, a mixing reactor, a neutralization reactor, and an ultrasonic leaching device, connected sequentially according to the material leaching sequence. A screening machine is provided between the crusher and the calcining furnace to screen the phosphate rock crushed by the crusher. A stirring blade structure is provided in the high-pressure reactor, the frozen crystallization tank, the mixing reactor, and the neutralization reactor, driven by a motor. A filter press is connected after the mixing reactor.

[0006] As an improvement of this utility model, the crusher is either a jaw crusher or a hammer crusher.

[0007] As an improvement of this utility model, the screen opening diameter of the sieve machine is less than or equal to 0.3mm.

[0008] As an improvement of this utility model, a filter and a washing tank are provided between the high-pressure reactor and the acid hydrolysis tank. The inlet end of the filter is connected to the outlet end of the high-pressure reactor and the washing tank. The washing tank washes the product from the high-pressure reactor so that it enters the filter and then enters the acid hydrolysis tank through the filter.

[0009] As an improvement of this utility model, the filter press is either a plate and frame filter press or a belt filter press.

[0010] As an improvement of this utility model, the ultrasonic leaching device includes a frequency-adjustable ultrasonic generator and a ceramic membrane filter.

[0011] As an improvement of this utility model, the stirring blade structure is located at the center of the freezing crystallization tank, the mixing reaction vessel, and the neutralization reaction vessel, and the stirring blade structure includes a rotating shaft and blades inclinedly arranged on the rotating shaft.

[0012] As an improvement of this utility model, the surface of the blade is provided with an overflow hole, and a filter membrane is provided in the overflow hole.

[0013] As an improvement of this utility model, the feed end of the neutralization reactor is connected to an ammonia tank, and then connected to a reslurry tank.

[0014] The beneficial effects of this utility model are as follows: Compared with the prior art, this utility model provides a system for producing crude rare earth from Zhijin rare earth-containing phosphate rock through high-pressure nitric acid multi-stage leaching and decomposition. The system includes a crusher, a calcining furnace, a high-pressure reactor, an acid leaching tank, a first centrifugal filter, a freezing crystallization tank, a second centrifugal filter, a mixing reactor, a neutralization reactor, and an ultrasonic leaching device, connected sequentially according to the material leaching sequence. A screening machine is provided between the crusher and the calcining furnace to screen the phosphate rock crushed by the crusher. Stirring blades are installed in the high-pressure reactor, the freezing crystallization tank, the mixing reactor, and the neutralization reactor. The structure consists of a stirring blade driven by a motor; a filter press is connected after the mixing reactor; this invention uses a high-pressure reactor to leach phosphate rock with nitric acid, combined with a multi-stage leaching process to purify and extract rare earth elements. Through the leaching action of multi-stage nitric acid, the elements in the Zhijin phosphate rock are gradually dissolved and separated, and impurities are removed through acid hydrolysis, freeze crystallization, and deep decalcification steps. Then, secondary leaching is achieved through the acoustic cavitation effect of an ultrasonic device to improve the leaching rate of rare earth elements in the filter cake, resulting in a crude rare earth enrichment. This invention improves the rare earth leaching efficiency of Zhijin phosphate rock to 99%, while utilizing fertilizer as a by-product of the nitric acid phosphate fertilizer plant. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the main structure of this utility model;

[0016] Figure 2 This is a first perspective view of the stirring blade assembly of this utility model;

[0017] Figure 3 This is a second perspective view of the stirring blade assembly of this utility model;

[0018] Figure 4 This is a schematic diagram of the structure of this utility model.

[0019] The symbols for the main components are explained below:

[0020] 1. Crusher; 2. Calcination furnace; 3. Screening machine; 4. Lime slurry supply tank; 5. Nitric acid storage tank; 6. High-pressure reactor; 7. Acid hydrolysis tank; 8. Wash water tank; 9. First centrifugal filter; 10. Freezing crystallization tank; 11. Second centrifugal filter; 12. Mixing reactor; 13. Filter press; 14. Neutralization reactor; 15. Ultrasonic leaching device; 16. Stirring blade structure; 161. Rotating shaft; 162. Paddle; 163. Overflow hole; 164. Filter membrane. Detailed Implementation

[0021] To more clearly illustrate this utility model, the following description, in conjunction with the accompanying drawings, will provide a further picture.

[0022] In the following description, specific examples are given to provide a more in-depth understanding of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of them. It should be understood that the specific embodiments described are only used to explain the present invention and are not intended to limit the present invention.

[0023] It should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of the said feature, integral, step, operation, element, or component, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, or combinations thereof.

[0024] Please see Figure 1This invention discloses a system for producing crude rare earth from rare earth-containing phosphate rock in Zhijin by high-pressure nitric acid multi-stage leaching and decomposition. The system comprises, in sequence according to the material leaching order, a crusher 1, a calcining furnace 2, a high-pressure reactor 6, an acid hydrolysis tank 7, a first centrifugal filter 9, a freezing crystallization tank 10, a second centrifugal filter 11, a mixing reactor 12, a neutralization reactor 14, and an ultrasonic leaching device 15. A screening machine 3 is installed between the crusher 1 and the calcining furnace 2 to screen the phosphate rock crushed by the crusher 1. The system is further integrated into the high-pressure reactor 6, freezing crystallization tank 10, mixing reactor 12, and neutralization reactor 14. A stirring blade structure 16 is provided, driven by a motor; a filter press 13 is connected after the mixing reactor 12; a sieve 3 can screen the crushed phosphate rock, which is more conducive to the thorough calcination in the calcining furnace 2. A high-pressure reactor 6 is connected to a nitric acid storage tank and a lime slurry supply tank. The high-pressure reactor 6 can provide a high-pressure environment for the phosphate rock and nitric acid, so that the nitric acid can fully react with the phosphate rock, separating the large amount of impurities and the phosphate concentrate with fewer impurities from the high-pressure leaching phosphate rock. The pH value is adjusted by lime slurry supplied by the lime slurry supply tank, and then... Subsequent acid hydrolysis involves further leaching with nitric acid to decompose the remaining fluorapatite and release the encapsulated rare earth elements. Solid-liquid separation is then performed using a first centrifugal filter 9, with the addition of wash water to thoroughly separate the acid hydrolysis solution and residue rich in rare earth elements. The acid hydrolysis solution is then placed in a cryogenic crystallization tank 10 for low-temperature cryogenic crystallization. Under low-temperature conditions, calcium ions in the acid hydrolysis solution are initially separated and precipitated. A second centrifugal filter 11 is then used to separate the crystallization mother liquor and calcium nitrate crystals. Finally, sulfuric acid solution is added to a mixing reactor 12 to further precipitate the calcium ions in the crystallization mother liquor. Decalcification is performed by solid-liquid separation using a plate and frame filter press 13, allowing calcium ions to be fully released and producing a deeply decalcified filtrate and a decalcified filter cake. The pH of the deeply decalcified filtrate is adjusted to approximately 6.0-7.0 using a neutralization reactor 14. Resizing water and washing water are then added, and finally, the deeply decalcified filtrate is leached using an ultrasonic leaching device 15. The ultrasonic waves generated in the liquid by the ultrasonic leaching device 15 can enhance the permeability of the washing water to the filter cake. Through the acoustic cavitation effect, coarse rare earth enrichment and resizing filtrate are separated, greatly improving the yield of coarse rare earth enrichment and the leaching rate of rare earth elements.

[0025] In this embodiment, the phosphate rock needs to be crushed by a jaw crusher 1 or a hammer crusher 1 first. The crushed phosphate rock can react more thoroughly in the subsequent calcination or acid hydrolysis process, thereby effectively separating the substances in the phosphate rock and crushing the phosphate rock particles to a size of less than or equal to 0.3 mm. Then, it is screened through a filter screen with a mesh diameter of less than 0.3 mm to ensure that the phosphate rock particle size does not exceed 0.3 mm. The screened phosphate rock fragments are added to the calcining furnace 2 and calcined at a calcination temperature of 900°C for 2 hours to generate calcined ore and release waste gas containing CO2. The calcining furnace 2 can be equipped with a waste gas recovery port to recover CO2 and prevent atmospheric pollution.

[0026] In this embodiment, a filter and a washing tank 8 are provided between the high-pressure reactor 6 and the acid hydrolysis tank 7. The inlet end of the filter is connected to the outlet end of the high-pressure reactor 6 and the washing tank 8. The washing tank 8 washes the product from the high-pressure reactor 6 so that it enters the filter and then enters the acid hydrolysis tank 7. The washing tank 8 washes the product from the high-pressure reactor 6, and the filter then filters it, so that solid and liquid are separated.

[0027] In this embodiment, the filter press 13 is either a plate and frame filter press 13 or a belt filter press 13. Both the plate and frame filter press 13 and the belt filter press 13 can perform solid-liquid separation on the crystallization mother liquor after deep decalcification. Because calcium ions are precipitated as CaSO4 particles under the action of sulfuric acid solution, the purity of rare earth ions in the solution is improved. Then, the CaSO4 particles are retained by the plate and frame filter press 13 or the belt filter press 13 to separate the deep decalcified filtrate containing rare earth ions.

[0028] In this embodiment, the ultrasonic leaching device 15 includes a frequency-adjustable ultrasonic generator and a ceramic membrane filter. This invention utilizes the acoustic cavitation effect to perform secondary leaching of the deep decalcification filtrate. The acoustic cavitation effect is caused by the action of ultrasonic waves in the liquid, resulting in a local pressure reduction in the liquid, causing dissolved gas or vapor to form microbubbles. These bubbles undergo expansion, oscillation, and violent collapse processes with changes in sound pressure. The ultrasonic waves generated by the ultrasonic device disperse the soft aggregates of rare earth hydroxides in the deep decalcification filtrate, stripping impurity ions adsorbed on the particle surface, promoting the lattice reconstruction of rare earth ions, and finally precipitating coarse rare earth enrichment, thereby improving the leaching rate and efficiency of rare earths.

[0029] In this embodiment, the stirring blade structure 16 is located at the center of the freezing crystallization tank 10, the mixing reactor 12, and the neutralization reactor 14. The stirring blade structure 16 includes a rotating shaft 161 and blades 162 inclined on the rotating shaft 161. The stirring blade structure 16 automatically stirs the reactions occurring in each reactor, eliminating the need for manual labor, controlling the efficiency of the chemical reaction, and controlling the stirring time to control the reaction progress. At the same time, an overflow hole 163 is provided on the surface of the blade 162, and a filter membrane 164 is provided in the overflow hole 163. When the blade 162 rotates and agitates the water, the water will pass through the overflow hole 163 and the filter membrane 164. The overflow hole 163 can reduce the rotational resistance of the blade 162, so that the particulate precipitates generated by the reaction are gathered at the position of the overflow hole 163 by centrifugal force and collected by the filter membrane 164, further improving the impurity removal rate and reducing the time spent in the subsequent washing and filtration process, thereby improving the leaching efficiency of rare earth.

[0030] In this embodiment, the feed end of the neutralization reactor 14 is connected to an ammonia tank, followed by a reslurry tank. The pH value of the deep decalcification filtrate is neutralized by ammonia and adjusted to 6.0-7.0. Then, it is mixed and washed together with the reslurry tank and enters the final ultrasonic leaching device 15.

[0031] The advantages of this utility model are:

[0032] This invention employs a high-pressure reactor to leach phosphate rock with nitric acid, combined with a multi-stage leaching process to purify and extract rare earth elements. Through multi-stage nitric acid leaching, the elements in the Zhijin phosphate rock are gradually dissolved and separated. Impurities are removed through acid hydrolysis, freeze crystallization, and deep decalcification. Then, secondary leaching is achieved through the acoustic cavitation effect of an ultrasonic device, increasing the leaching rate of rare earth elements in the filter cake and obtaining a crude rare earth enrichment. This increases the rare earth leaching efficiency of Zhijin phosphate rock to 99%, while utilizing fertilizer as a byproduct of the nitric acid phosphate fertilizer plant.

[0033] The above-disclosed embodiments are only a few specific examples of this utility model. However, this utility model is not limited thereto. Any variations that can be conceived by those skilled in the art should fall within the protection scope of this utility model.

Claims

1. A system for extracting crude rare earth elements from Zhijin rare earth-containing phosphate rock by high-pressure nitric acid multi-stage leaching and decomposition, characterized in that, The system includes a crusher, a calcining furnace, a high-pressure reactor, an acid hydrolysis tank, a first centrifugal filter, a frozen crystallization tank, a second centrifugal filter, a mixing reactor, a neutralization reactor, and an ultrasonic leaching device, connected sequentially according to the material leaching sequence. A sieve is installed between the crusher and the calcining furnace to screen the phosphate rock crushed by the crusher. The high-pressure reactor, the frozen crystallization tank, the mixing reactor, and the neutralization reactor are equipped with stirring blade structures driven by motors. A filter press is connected after the mixing reactor.

2. The system for producing crude rare earth from Zhijin rare earth-bearing phosphate rock by high-pressure nitric acid multi-stage leaching and decomposition according to claim 1, characterized in that, The crusher is either a jaw crusher or a hammer crusher.

3. The system for producing crude rare earth from rare earth by high-pressure nitric acid multi-stage leaching and decomposition of rare earth-containing phosphate rock in Zhijin, as described in claim 1, is characterized in that... The screen opening diameter of the sieve machine is less than or equal to 0.3 mm.

4. The system for producing crude rare earth from Zhijin rare earth-bearing phosphate rock by high-pressure nitric acid multi-stage leaching and decomposition according to claim 1, characterized in that, A filter and a washing tank are provided between the high-pressure reactor and the acid hydrolysis tank. The inlet end of the filter is connected to the outlet end of the high-pressure reactor and the washing tank. The washing tank washes the product from the high-pressure reactor so that it enters the filter and then enters the acid hydrolysis tank.

5. The system for producing crude rare earth from Zhijin rare earth-bearing phosphate rock by high-pressure nitric acid multi-stage leaching and decomposition according to claim 1, characterized in that, The filter press is either a plate and frame filter press or a belt filter press.

6. The system for producing crude rare earth from Zhijin rare earth-bearing phosphate rock by high-pressure nitric acid multi-stage leaching and decomposition according to claim 1, characterized in that, The ultrasonic leaching device includes a frequency-adjustable ultrasonic generator and a ceramic membrane filter.

7. The system for producing crude rare earth from Zhijin rare earth-containing phosphate rock by high-pressure nitric acid multi-stage leaching and decomposition according to claim 1, characterized in that, The stirring blade structure is located at the center of the freeze crystallizer, the mixing reactor, and the neutralization reactor. The stirring blade structure includes a rotating shaft and blades inclinedly arranged on the rotating shaft.

8. The system for producing crude rare earth from Zhijin rare earth-bearing phosphate rock by high-pressure nitric acid multi-stage leaching and decomposition according to claim 7, characterized in that, The surface of the blade is provided with overflow holes, and a filter membrane is provided in the overflow holes.

9. The system for producing crude rare earth from Zhijin rare earth-bearing phosphate rock by high-pressure nitric acid multi-stage leaching and decomposition according to claim 1, characterized in that, The feed end of the neutralization reactor is connected to an ammonia tank, and then to a reslurry tank.

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