Leaching agent for leaching ionic rare earth ore and leaching method thereof

Abstract

The present invention discloses a leaching agent and a leaching method for leaching ionic rare earth ores. The leaching agent uses a salt solution containing rare earths, particularly lanthanum and cerium, and controls the concentration of cations other than hydrogen ions in the leaching agent to 0.06-0.12 mol / L. By utilizing the high leaching capacity of high-valent cations for ionic rare earth ores, the leaching agent achieves efficient rare earth leaching at low leaching agent concentrations. This method also adds new applications for surplus lanthanum and cerium, reducing waste of these elements. In particular, the leaching agent adopts a pipeline leaching method to effectively increase the concentration of the rare earth leachate.

Description

Technical Field

[0001] The present invention relates to the field of rare earth resource extraction, and in particular to a leaching agent for leaching ionic rare earth ores and a leaching method thereof. Background Art

[0002] Ionic rare earth ores, also known as southern rare earth ores, ion adsorption rare earth ores, and weathering crust elution rare earth ores, were first discovered in Longnan, China. Since then, with the widespread application of rare earths, exploration has flourished, with discoveries occurring in seven provinces in my country, namely Jiangxi, Fujian, Guangxi, Guangdong, Hunan, Yunnan, and Zhejiang, as well as in Myanmar, the Philippines, Malaysia, Chile, Brazil, and Madagascar. Ionic rare earth ores are strategic mineral resources in my country, characterized by a complete rare earth distribution, low radioactivity, ease of extraction, large reserves, and rich concentrations of medium and heavy rare earth elements.

[0003] Ionic rare earth ores are of relatively low grade, with rare earth oxide content of only 0.05%-0.2%. Rare earth elements (REs) occur in four forms within ionic rare earth ores: ionic, colloidal, mineral, and water-soluble. Ionic REs account for the largest proportion, accounting for 80% of the total rare earth content. They are adsorbed on clay minerals in the form of hydroxyl groups or hydrated hydroxyl groups, which can exchange and desorb the REs from clay minerals with chemically active cations. Leaching agents, such as sodium chloride, ammonium sulfate, and magnesium sulfate, have been developed to recover rare earth resources. However, the leaching efficiency of these agents is only approximately 92%, and the concentration of the leaching agent used is as high as 0.20 mol / L, resulting in a waste of rare earth resources. To improve the leaching efficiency of ionic REs, researchers have developed a series of enhanced leaching methods and new ammonium-free leaching agents. In terms of enhanced leaching, the introduction and use of organic additives such as fulvic acid, tianqing gum, citric acid, and ascorbic acid, as well as technologies such as magnetic fields, ultrasound, and microwaves, can effectively increase rare earth leaching rates. However, these enhanced leaching processes are hindered by cost, organic pollution, and compatibility with mining environments. Meanwhile, some researchers have proposed using high-valent cationic leaching agents such as aluminum sulfate and iron sulfate to leach ionic rare earth ores, which can improve rare earth leaching rates. However, the introduction of aluminum and iron increases the load on the rare earth leachate enrichment and poses environmental risks to mines and water bodies.

[0004] Therefore, developing efficient leaching agents to improve rare earth leaching efficiency, reduce leaching agent consumption, and achieve efficient extraction of ionic rare earth ores has become a technical issue that is currently being focused on and resolved. Summary of the Invention

[0005] The primary objective of the present invention is to provide a leaching agent and leaching method for leaching ionic rare earth ores, thereby reducing leaching agent concentration, increasing rare earth leaching efficiency, and enabling the use of surplus lanthanum, cerium, and rare earth. To achieve these objectives, the present invention provides, in one aspect, a leaching agent for leaching ionic rare earth ores. The leaching agent is a salt solution containing rare earths, wherein the concentration of cations other than hydrogen ions in the leaching agent is 0.06-0.12 mol / L; the rare earth is at least one of lanthanum and cerium.

[0006] Furthermore, the rare earth-containing salt solution also includes one or more of aluminum ions, iron ions, magnesium ions, and calcium ions; and the molar ratio of non-rare earth elements to rare earth elements in the leaching agent is ≤1.0.

[0007] Furthermore, the leaching agent is a solution obtained by degreasing and diluting the wastewater containing lanthanum cerium chloride produced in the extraction and separation section of an industrial NdFeB waste recycling enterprise.

[0008] Furthermore, the extractant also contains at least one of alkyl glycoside, fatty alcohol polyoxyethylene ether ammonium sulfate, lignin sulfonate, stearic acid glycerol monoester, cocamidopropyl betaine, and dodecyltrimethylammonium chloride, and the concentration thereof is 0.001 mol / L-0.005 mol / L.

[0009] Another aspect of the present invention provides a method for leaching ionic rare earth ore using the above-mentioned leaching agent, comprising the following steps: using the ionic rare earth ore as raw material, leaching the ionic rare earth ore using the leaching agent, and then washing with top water to finally obtain rare earth leachate and rare earth tailings.

[0010] Furthermore, the ionic rare earth ore is loaded into a pipeline with an aspect ratio of 1000-2000, and the overall loading height should be more than 800 times the diameter of the pipeline; the negative pressure at the pipeline outlet is controlled to be 10Kpa-50Kpa, and then the leaching agent is added at the pipeline inlet to finally obtain rare earth leachate and rare earth tailings.

[0011] This invention utilizes a salt solution containing rare earth elements, particularly lanthanum and cerium, as a leaching agent. Leveraging the high leaching capacity of high-valent cations for ionic rare earth ores, this method achieves efficient rare earth leaching at low leaching agent concentrations. This also adds new applications for surplus lanthanum and cerium, reducing waste. In particular, the use of a pipeline leaching method effectively increases the concentration of the rare earth leachate. DETAILED DESCRIPTION

[0012] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the embodiments.

[0013] Ionic rare earth ores are rich in high-value medium and heavy rare earth elements and are important strategic mineral resources in my country. Currently, the industry uses approximately 2% ammonium sulfate and magnesium sulfate to leach the ionic rare earths from ionic rare earth ores, resulting in a leaching rate of only around 92%. Furthermore, the concentration of rare earths in the leachate is relatively low, below 1.0 g / L, increasing the operational load for subsequent enrichment.

[0014] To this end, the present invention provides, on one hand, a leaching agent for leaching ionic rare earth ores. The leaching agent is a rare earth-containing salt solution, wherein the concentration of cations other than hydrogen ions in the leaching agent is 0.06-0.12 mol / L. The rare earth is at least one of lanthanum and cerium. Currently, the production and application of light rare earths such as lanthanum and cerium are insufficient, resulting in a relatively low price for lanthanum-cerium oxide. Using a rare earth-containing salt solution as a leaching agent, on the one hand, due to its high valence and strong leaching capacity, can achieve high rare earth leaching rates at relatively low concentrations. This also results in a relatively high leachate concentration, which reduces the tailing phenomenon and reduces the burden on subsequent impurity removal and enrichment steps. Furthermore, as surplus elements, lanthanum and cerium can be retained in the tailings after leaching, providing a strategic storage effect. When the price and application of lanthanum and cerium increase, they can be leached and reused using non-rare earth leaching agents. The rare earth-containing salt solution can also contain one or more of aluminum, iron, magnesium, and calcium ions, thereby reducing the amount of lanthanum and cerium required and achieving a synergistic leaching. However, to ensure high leaching efficiency, the molar ratio of non-rare earth elements to rare earth elements in the leachate must be ≤ 1.0. Furthermore, during the rare earth smelting and separation process, many lanthanum and cerium-containing solutions, such as those from polishing powder waste leachate and crude lanthanum and cerium solutions from extraction and separation, contain non-rare earth impurities such as calcium and magnesium.

[0015] In particular, the rare earth-containing salt solution is a solution obtained by degreasing and diluting the wastewater containing lanthanum cerium chloride produced in the extraction and separation section of industrial NdFeB waste recycling companies. Generally, NdFeB waste recycling companies use a hydrochloric acid solution-extraction separation-precipitation and roasting process to recover rare earths. However, during the extraction and separation process, a lanthanum cerium salt solution is produced. If this solution is used to obtain rare earth oxides by precipitation, the product price is not enough to offset the cost of the precipitation and roasting process. Therefore, this part of the lanthanum cerium-containing solution is directly sent to the wastewater treatment process as wastewater, resulting in a waste of rare earth resources. This part of the lanthanum cerium chloride-containing wastewater is degreased to reduce the impact of its oil content on mine leaching, and is diluted to the concentration required by the leaching agent, thereby achieving efficient leaching of ion ore.

[0016] In the above-mentioned method provided by the invention, the leaching agent further contains at least one of alkyl glycoside, fatty alcohol polyoxyethylene ether ammonium sulfate, lignin sulfonate, stearic acid glyceryl monoester, cocamidopropyl betaine, and lauryl trimethyl ammonium chloride, with a concentration of 0.001 mol / L to 0.005 mol / L. The presence of alkyl glycoside, fatty alcohol polyoxyethylene ether ammonium sulfate, lignin sulfonate, stearic acid glyceryl monoester, cocamidopropyl betaine, and lauryl trimethyl ammonium chloride has two functions: first, interacting with the clay mineral-water interface to increase the leaching agent's penetration rate; second, complexing with rare earth elements. Both functions facilitate enhanced leaching of rare earth elements and reduce the required cation concentration in the leaching agent.

[0017] Another aspect of the present invention provides a method for leaching ionic rare earth ores using the aforementioned leaching agent, comprising the steps of: using an ionic rare earth ore as a raw material, leaching the ionic rare earth ore using the aforementioned leaching agent, and then washing the ore with topwater to obtain a rare earth leachate and rare earth tailings. The leaching agent is a salt solution containing rare earths, wherein the concentration of cations other than hydrogen ions in the leaching agent is 0.06-0.12 mol / L, and the rare earth is at least one of lanthanum and cerium. The leaching agent may also contain non-rare earth elements such as calcium, magnesium, iron, and aluminum, but the molar ratio of non-rare earth elements to rare earth elements is ≤ 1.0. Furthermore, the leaching agent may also contain at least one of alkyl glycoside, fatty alcohol polyoxyethylene ether ammonium sulfate, lignin sulfonate, stearic acid glycerol monoester, cocamidopropyl betaine, and dodecyltrimethylammonium chloride, at a concentration of 0.001-0.005 mol / L. By controlling the concentration and amount of cations and organic matter in the leaching agent, a higher rare earth leaching rate can be achieved. The leaching methods of ionic rare earth ores can be pool leaching, heap leaching, in-situ leaching, etc.

[0018] Furthermore, ionic rare earth ores are leached using a pipeline leaching method. Specifically, the ionic rare earth ore is loaded into a pipeline with an aspect ratio of 1000-2000, and the overall loading height is at least 800 times the pipeline diameter. A negative pressure of 10 kPa-50 kPa is maintained at the pipeline outlet. The leaching agent is then added at the pipeline inlet, ultimately producing a rare earth leachate and rare earth tailings. This pipeline leaching method, with an aspect ratio of 1000-2000 and an overall loading height of at least 800 times the pipeline diameter, increases the number of adsorption, desorption, and ion exchange events in the clay mineral, thereby increasing the rare earth concentration in the leachate. To ensure proper flow of the leaching agent in pipelines with high aspect ratios, a negative pressure of 10 kPa-50 kPa is required at the pipeline outlet. The higher the loading height and the smaller the pipeline diameter, the lower the negative pressure needs to be.

[0019] The following will further illustrate a leaching agent for leaching ionic rare earth ores and a leaching method thereof provided by the present invention with reference to examples.

[0020] Comparative Example 1

[0021] Ionic rare earth ore (medium yttrium-rich europium type, rare earth grade 0.0 ...

[0022] Example 1

[0023] Ionic rare earth ore (medium yttrium-rich europium type, rare earth grade 0.0 ...

[0024] Example 2

[0025] Ionic rare earth ore (medium yttrium-rich europium type, rare earth grade 0.0 ...

[0026] Example 3

[0027] Ionic rare earth ore (medium yttrium-rich europium type, rare earth grade 0.0 ...

[0028] Example 4

[0029] Ionic rare earth ore (medium yttrium-rich europium type, rare earth grade 0.0 ...

[0030] Example 5

[0031] Ionic rare earth ore (medium yttrium-rich europium type, rare earth grade 0.0 ...

[0032] Example 6

[0033] Ionic rare earth ore (medium yttrium-rich europium type, rare earth grade 0.0 ...

Claims

1. A leaching agent for leaching ionic rare earth ores, characterized in that: The leaching agent is a salt solution containing rare earth, and the concentration of cations other than hydrogen ions in the leaching agent is 0.06-0.12 mol / L; the rare earth is at least one of lanthanum and cerium; the leaching agent also contains at least one of alkyl glycoside, fatty alcohol polyoxyethylene ether ammonium sulfate, lignin sulfonate, stearic acid glyceryl monoester, and cocamidopropyl betaine.

2. The leaching agent according to claim 1, characterized in that The rare earth-containing salt solution also includes one or more of aluminum ions, iron ions, magnesium ions, and calcium ions; and the molar ratio of non-rare earth elements to rare earth elements in the leaching agent is ≤1.

0.

3. The leaching agent according to claim 1, characterized in that The leaching agent is a solution obtained by degreasing and diluting wastewater containing lanthanum cerium chloride produced in the extraction and separation section of an industrial NdFeB waste recycling enterprise.

4. The leaching agent according to claim 1, characterized in that The total concentration of alkyl glycoside, fatty alcohol polyoxyethylene ether ammonium sulfate, lignin sulfonate, stearic acid glycerol monoester and cocamidopropyl betaine contained in the extractant is 0.001 mol / L-0.005 mol / L.

5. A method for leaching ionic rare earth ores using the leaching agent according to any one of claims 1 to 4, characterized in that: The following steps are involved: The ionic rare earth ore is taken as a raw material, the ionic rare earth ore is leached with the leaching agent, and then top water is used for washing to finally obtain rare earth leaching solution and rare earth tailings.

6. The method according to claim 5, characterized in that The ionic rare earth ore is loaded into a pipeline with an aspect ratio of 1000-2000, and the overall loading height should be more than 800 times the diameter of the pipeline; the negative pressure at the pipeline outlet is controlled to be 10Kpa-50Kpa, and then the leaching agent is added at the pipeline inlet to finally obtain rare earth leachate and rare earth tailings.