A surfactant composite leaching agent for weathering crust type rare earth ore

Abstract

This invention discloses a surfactant-based composite leaching agent for weathered crust leached rare earth ores. It is a composite solution formed primarily from a composite cationic surfactant and an inorganic leaching agent solution. The composite cationic surfactant is composed of hexadecyltrimethylammonium bromide and dodecyltrimethylammonium bromide. This surfactant-based composite leaching agent effectively increases the penetration rate of the leaching agent solution into the ore body, increases the leaching rate of rare earth elements, inhibits the leaching of aluminum impurities, and suppresses the expansion of the ore body, thus maximizing the leaching process of rare earth elements. Furthermore, the application method is simple, efficient, and suitable for widespread application.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, specifically relating to a surfactant composite leaching agent for weathered crust leached rare earth ores. Background Technology

[0002] Weathering crust leaching rare earth deposits are rich in medium and heavy rare earth elements, possessing significant industrial value and representing a valuable mineral resource in my country. In these deposits, rare earth elements are adsorbed onto the surface of clay minerals as hydrated ions or hydroxyl hydrated ions. Conventional physical beneficiation methods cannot enrich these rare earth elements; only chemical beneficiation methods, through ion exchange, can concentrate rare earth ions in the solution.

[0003] Currently, weathered crust leaching-type rare earth deposits are mainly mined using in-situ leaching, a process involving ion exchange chemical leaching and the physical transport of the solution during seepage. Weathered crust leaching-type rare earth deposits are primarily composed of clay minerals, thus exhibiting characteristics such as fine particle size, large specific surface area, low porosity, and poor permeability. This results in slow seepage of the leaching agent solution within the ore body, leading to a long production cycle and significantly impacting the mining and utilization of rare earth deposits. Furthermore, impurity ions in the ore body also enter the solution to varying degrees during rare earth leaching, reducing the purity of the rare earth product and increasing production costs. Aluminum is the most significant impurity ion. To achieve green and efficient development of weathered crust leaching-type rare earth deposits, a suitable leaching aid is urgently needed to increase the seepage rate of the leaching agent solution within the ore body, promote the seepage process of rare earth leaching, improve leaching efficiency, and simultaneously inhibit the leaching of aluminum impurities.

[0004] When leaching weathered crust leached rare earth ores with traditional single leaching agents, clay minerals adsorb a large amount of the leaching solution, increasing the thickness of the water film on the surface of the clay minerals. This directly affects the seepage channels, reduces the permeability coefficient of the ore body, and affects the seepage rate, leading to a decrease in rare earth leaching efficiency. Studies have shown that adding a certain amount of leaching aid to the leaching agent can effectively solve this problem. Surfactants have an amphiphilic structure; the presence of hydrophilic groups such as carboxylic acids and hydroxyl groups can significantly reduce the surface tension of the solution, reduce the thickness of the water film on the mineral surface, improve the wettability of the mineral surface, and make it easier for the solution to penetrate into the fine pores of the ore body. This enhances the permeability of the leaching agent solution in the ore body and strengthens the seepage process of rare earth leaching. The nonpolar carbon atoms and hydrocarbon chains in surfactants also have good hydrophobic properties. When the cations in the leaching agent solution undergo ion exchange reactions with the adsorbed solid rare earth ions in the ore body, the free rare earth ions can accelerate the ion diffusion rate in the presence of hydrophobic groups, which can effectively improve the leaching efficiency of rare earths and shorten the time to reach leaching equilibrium. Furthermore, during the leaching process, clay minerals easily expand upon contact with water, disrupting the inherent structure of the ore body and potentially causing instability, leading to geological disasters such as landslides. This not only renders landslide-affected ore bodies unmineable, wasting valuable rare earth resources, but also damages farmland beneath the ore body, creating safety issues in rare earth mining and threatening the ecological environment of the mining area.

[0005] In recent years, surfactants have been widely used as leaching aids in enhancing the leaching of rare earth minerals. Surfactants can regulate the physicochemical properties of the leaching agent solution and the surface of mineral particles, enhance the exchange and diffusion process at the mineral-liquid interface, inhibit the swelling of clay minerals, and prevent landslide geological hazards. However, single surfactants have few hydrophilic and hydrophobic groups and are difficult to adsorb onto the solid-liquid interface and mineral surface, thus failing to produce good effects in promoting penetration, inhibiting aluminum, and preventing swelling. Summary of the Invention

[0006] The purpose of this invention is to address the problems and shortcomings of existing technologies by providing a surfactant composite leaching agent for weathered crust leached rare earth ores. This agent can effectively increase the penetration rate of the leaching agent solution in the ore body, increase the leaching rate of rare earths, inhibit the leaching of aluminum impurities and inhibit the expansion of the ore body, and maximize the leaching process of rare earths. Furthermore, the application method involved is simple, efficient, and suitable for widespread application.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A surfactant composite leaching agent for weathered crust leached rare earth minerals is a composite solution formed mainly from a composite cationic surfactant and an inorganic leaching agent solution; the composite cationic surfactant is composed of hexadecyltrimethylammonium bromide and dodecyltrimethylammonium bromide.

[0009] In the above scheme, the hexadecyltrimethylammonium bromide and dodecyltrimethylammonium bromide are compounded at a mass ratio of 1:(0.8-1.5).

[0010] In the above scheme, the inorganic leaching agent is one of ammonium sulfate, ammonium chloride, and magnesium sulfate.

[0011] In the above scheme, the concentration of surfactant in the composite extractant is 0.01 to 0.05 wt%.

[0012] In the above scheme, the concentration of the inorganic leaching agent solution in the composite leaching agent is 0.1 to 0.3 mol / L.

[0013] Preferably, the inorganic leaching agent solution is ammonium sulfate with a concentration of 0.1 mol / L.

[0014] The surfactant and compound surfactant leaching agent solutions obtained from the above scheme were applied to the leaching of weathered crust leached rare earth ores.

[0015] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0016] 1) Compared with traditional leaching agents, the surfactant composite leaching agent of the present invention can effectively enhance seepage, increase the permeability coefficient, increase the rare earth leaching rate, inhibit the leaching of aluminum impurities, inhibit the expansion of the ore body, and enhance the rare earth leaching process.

[0017] 2) Compared with single-category surfactant compound leaching solutions, the surfactant composite leaching agent described in this invention can maximize the amphiphilic properties of surfactants, effectively solving the problem that single surfactants have fewer hydrophilic and hydrophobic groups and are difficult to adsorb onto the solid-liquid interface and mineral surface. This improves the properties of surfactants, significantly reduces the surface tension of the leaching agent solution entering the ore body, maximizes the properties of surfactants, and further enhances the rare earth leaching process. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] In the following examples, a column leaching test was used to simulate the in-situ leaching process of rare earth minerals. The basic operating steps were as follows: 150g of mixed rare earth mineral sample, dried in a 50℃ drying oven, was weighed on an electronic balance using the quartering method. The sample was evenly packed into a glass leaching column, and 1-2 layers of filter paper were placed flat on the sample. Humic acid-ammonium sulfate compound leaching solution was added at a constant flow rate using a constant flow peristaltic pump to leach the rare earth. The rare earth leachate in the glass column was collected using a precision graduated cylinder, and its volume was measured. Subsequently, the content of rare earth and aluminum in the leaching solution was determined by EDTA complexometric titration. The permeability coefficient was calculated using Darcy's law.

[0020] Example 1

[0021] A cationic surfactant composite leaching agent for weathered crust leached rare earth deposits, specifically for a weathered crust leached rare earth deposit in Jiangxi Province with an average rare earth grade of 0.14%; the specific preparation and application steps of the composite leaching agent are as follows:

[0022] Ammonium sulfate, CTAB, and DTAB are uniformly dispersed in water, wherein the concentration of ammonium sulfate is 0.2 mol / L, the mass concentration of CTAB is 0.02%, and the mass concentration of DTAB is 0.02%, thus obtaining the composite leaching agent.

[0023] The composite leaching agent obtained in this embodiment was applied to weathered crust leaching rare earth ore. A column leaching test was used to simulate the in-situ leaching process of rare earth ore. The column height of the weathered crust leaching rare earth ore was 4 cm, and the column height of the composite leaching agent solution was 8 cm. Rare earth leachate was obtained by leaching. The permeability coefficient was calculated using Darcy's law, and the content of rare earth and aluminum in the leachate was determined by EDTA volumetric method.

[0024] Referring to the method described above, the composite leaching agent obtained in this embodiment was applied to the leaching of weathered crust leached rare earth ore. Calculations and analysis showed that the permeability coefficient of the ore body leached with the composite leaching agent obtained in this embodiment was 2.956 × 10⁻⁶. -5 cm·s -1 Compared with the single surfactant CTAB compound leaching agent described in Comparative Example 1, the permeability coefficient of the ore body increased by 1.078 × 10⁻⁶. -5 cm·s -1 The rare earth leaching rate was 98%, and the aluminum leaching rate was 53%. The expansion rate was 0.93%. Compared with Comparative Examples 2, 3, and 4, the composite leaching agent obtained in this embodiment improved the permeability coefficient and rare earth leaching rate of the ore body, and reduced the aluminum leaching rate and the expansion rate of the ore body when leaching rare earth ores.

[0025] Comparative Example 1

[0026] A cationic surfactant composite leaching agent for weathered crust leached rare earth deposits, specifically for a weathered crust leached rare earth deposit in Jiangxi Province with an average rare earth grade of 0.14%; the specific preparation and application steps of the composite leaching agent are as follows:

[0027] Ammonium sulfate and CTAB are uniformly dispersed in water, wherein the concentration of ammonium sulfate is 0.1 mol / L and the mass concentration of CTAB is 0.04%, thus obtaining the composite leaching agent;

[0028] The composite leaching agent obtained in this embodiment was applied to weathered crust leaching rare earth ore. A column leaching test was used to simulate the in-situ leaching process of rare earth ore. The column height of the weathered crust leaching rare earth ore was 4 cm, and the column height of the composite leaching agent solution was 8 cm. Rare earth leachate was obtained by leaching. The permeability coefficient was calculated using Darcy's law, and the content of rare earth and aluminum in the leachate was determined by EDTA volumetric method.

[0029] Calculations and analysis show that the permeability coefficient of rare earth ore obtained using the composite leaching agent described in this embodiment is 1.878 × 10⁻⁶. -5 cm·s -1 Compared to the traditional ammonium sulfate leaching agent described in Comparative Example 5, the permeability coefficient of the ore body increased by 0.853 × 10⁻⁶. -5 cm·s -1 The rare earth leaching rate was 90%, the aluminum leaching rate was 80%, and the expansion rate was 4.21%.

[0030] Comparative Example 2

[0031] A cationic surfactant composite leaching agent for weathered crust leached rare earth deposits, specifically for a weathered crust leached rare earth deposit in Jiangxi Province with an average rare earth grade of 0.14%; the specific preparation and application steps of the composite leaching agent are as follows:

[0032] Ammonium sulfate, CTAB, and SDS are uniformly dispersed in water, wherein the concentration of ammonium sulfate is 0.1 mol / L, the mass concentration of CTAB is 0.02%, and the mass concentration of SDS is 0.02%, thus obtaining the composite leaching agent.

[0033] Referring to the method described in Example 1, the composite leaching agent obtained in this example was applied to the leaching of weathered crust leached rare earth ore. Calculations and analysis showed that the permeability coefficient of the ore body leached with the composite leaching agent obtained in this example was 2.548 × 10⁻⁶. -5 cm·s -1 Compared with the single CTAB surfactant compound leaching agent described in Comparative Example 1, the permeability coefficient of the ore body increased by 0.67 × 10⁻⁶. -5 cm·s -1 The rare earth leaching rate was 95%, the aluminum leaching rate was 60%, and the expansion rate was 2.22%.

[0034] Comparative Example 3

[0035] A cationic surfactant composite leaching agent for weathered crust leached rare earth deposits, specifically for a weathered crust leached rare earth deposit in Jiangxi Province with an average rare earth grade of 0.14%; the specific preparation and application steps of the composite leaching agent are as follows:

[0036] Ammonium sulfate, CTAB, and oleic acid are uniformly dispersed in water, wherein the concentration of ammonium chloride is 0.2 mol / L, the mass concentration of CTAB is 0.02%, and the mass concentration of oleic acid is 0.02%, thus obtaining the composite leaching agent.

[0037] Referring to the method described in Example 1, the composite leaching agent obtained in this example was applied to the leaching of weathered crust leached rare earth ore. Calculations and analysis showed that the permeability coefficient of the ore body using the composite leaching agent obtained in this example was 2.156 × 10⁻⁶. -5 cm·s -1 Compared to the single CTAB surfactant compound leaching agent described in Comparative Example 1, the permeability coefficient of the ore body increased by 0.278 × 10⁻⁶. -5 cm·s -1 The rare earth leaching rate was 92%, the aluminum leaching rate was 70%, and the expansion rate was 3.92%.

[0038] Comparative Example 4

[0039] A cationic surfactant composite leaching agent for weathered crust leached rare earth deposits, specifically for a weathered crust leached rare earth deposit in Jiangxi Province with an average rare earth grade of 0.14%; the specific preparation and application steps of the composite leaching agent are as follows:

[0040] Ammonium sulfate, CTAB, and sodium oleate are uniformly dispersed in water, wherein the concentration of ammonium sulfate is 0.2 mol / L, the mass concentration of CTAB is 0.02%, and the mass concentration of sodium oleate is 0.02%, thus obtaining the composite leaching agent.

[0041] Referring to the method described in Example 1, the composite leaching agent obtained in this example was applied to the leaching of weathered crust leached rare earth ore. Calculations and analysis showed that the permeability coefficient of the ore body using the composite leaching agent obtained in this example was 2.3237 × 10⁻⁶. -5 cm·s -1 Compared to the single surfactant CTAB-based leaching agent described in Comparative Example 1, the permeability coefficient of the ore body increased by 0.3987 × 10⁻⁶. -5 cm·s -1 The rare earth leaching rate was 94%, and the aluminum leaching rate was 65%. The expansion rate was 3.12%.

[0042] Comparative Example 5

[0043] For a weathered crust leaching type rare earth deposit in Jiangxi Province with an average rare earth grade of 0.14%, a column leaching experiment was used to simulate the leaching process, using ammonium sulfate solution (concentration of 0.1 mol·L⁻¹). -1 As a leaching agent, the composite leaching agent obtained in this embodiment was applied to the leaching of weathered crust leached rare earth ore using the method described in Example 1. Calculations and analysis showed that the permeability coefficient of the traditional ammonium sulfate solution leaching agent was 1.025 × 10⁻⁶. -5 cm·s -1 The rare earth leaching rate was 84%, the aluminum leaching rate was 90%, and the expansion rate was 5.38%.

[0044] The above results show that the cationic surfactants CTAB and DTAB mixed in a 1:1 ratio to form a compound leaching agent significantly increases the permeability coefficient and rare earth leaching rate of the ore body compared to traditional leaching agents. It also effectively inhibits the leaching of aluminum impurities and the expansion of the ore body. Compared to a single CTAB surfactant compound leaching agent solution, it effectively solves the problem that single surfactants have fewer hydrophilic and hydrophobic groups and are difficult to adsorb onto the solid-liquid interface and mineral surface. This improves the properties of the surfactant, significantly reduces the surface tension of the leaching agent solution entering the ore body, maximizes the properties of the surfactant, and further enhances the rare earth leaching process.

[0045] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations; therefore, any obvious variations or modifications derived therefrom remain within the scope of protection of this invention.

Claims

1. A surfactant composite leaching agent for weathered crust leached rare earth minerals, characterized in that, It is a composite solution formed mainly from a complex cationic surfactant and an inorganic leaching agent solution; the complex cationic surfactant is composed of hexadecyltrimethylammonium bromide and dodecyltrimethylammonium bromide. The hexadecyltrimethylammonium bromide and dodecyltrimethylammonium bromide are compounded at a mass ratio of 1:(0.8~1.5); Compared with traditional leaching agents, the surfactant composite leaching agent can effectively enhance seepage, increase the permeability coefficient, increase the rare earth leaching rate, and inhibit the leaching of aluminum impurities and the expansion of the ore body; the expansion rate reaches 0.93% and the aluminum leaching rate reaches 53%.

2. The surfactant composite extractant according to claim 1, characterized in that, The inorganic leaching agent is one of ammonium sulfate, ammonium chloride, and magnesium sulfate.

3. The surfactant composite extractant according to claim 1, characterized in that, The concentration of surfactant in the composite extractant is 0.01~0.05wt%.

4. The surfactant composite extractant according to claim 1, characterized in that, The concentration of the inorganic leaching agent solution in the composite leaching agent is 0.1~0.3 mol / L.